diff --git a/CLAUDE.md b/CLAUDE.md
index 9fe7029..05f050f 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -14,11 +14,29 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 ./pi-stat -g / --geo             # With geolocation (implies -p)
 ./pi-stat -s / --show-ip         # Show IP column (hidden by default)
 ./pi-stat -x / --extended        # Show full RX/TX/RX-rate/TX-rate columns (default: ratio only)
-./pi-stat -i [SEC] / --interactive [SEC]  # Interactive auto-refresh (default: 10s)
+./pi-stat -i [SEC] / --interactive [SEC]  # Interactive auto-refresh (default: 5s, configurable)
 ```
 
 No build step. Requires `pip install docker` and a running Docker daemon. Runs on Linux, WSL2, and Windows.
 
+## Configuration
+
+Optional JSON config file, first match wins: `$PI_STAT_CONFIG` → `~/.config/pi-stat/config.json` → `<script dir>/pi-stat.json` (see `pi-stat.json`, shipped with the repo). Loaded by `load_config()`; missing, unreadable or non-object files fall back to defaults with a warning on stderr.
+
+| Key | Default | Meaning |
+| --- | --- | --- |
+| `refresh_interval` | `5` | Interactive auto-refresh interval in seconds (clamped to >= 1) |
+
+Precedence for the refresh interval: `-i SEC` on the command line > config file > `DEFAULT_REFRESH` (5).
+
+Standard JSON has no comment syntax; document settings with a `_comment` key instead (any key not read by `config_refresh()` is ignored), e.g.:
+```json
+{
+  "_comment": "refresh_interval in seconds, min. 1 (default: 5)",
+  "refresh_interval": 5
+}
+```
+
 ## Architecture
 
 Single self-contained script (`pi-stat`). Logic is split into helper functions and a `run_cycle()` function that collects data and renders one full screen, called either once (normal mode) or in a loop (interactive mode).
@@ -49,6 +67,8 @@ Single self-contained script (`pi-stat`). Logic is split into helper functions a
 
 Outbound peers are numbered in the table. Full node IDs are fetched via `peers?fullkeys=true` for the `droppeer` API call.
 
+The refresh deadline is anchored to the start of the cycle (`cycle_start`), not its end, so the update's own execution time doesn't stack on top of `refresh_interval`. Execution time is measured and a warning is printed (into the same buffered screen) when a cycle takes >= `REFRESH_WARN_RATIO` (80%) of the interval, or exceeds it outright.
+
 ### Key patterns
 
 - **Graceful degradation** — every external call is wrapped in try-except; missing data renders as `—`
@@ -57,3 +77,6 @@ Outbound peers are numbered in the table. Full node IDs are fetched via `peers?f
 - **Validator matching** — `load_validators()` parses `stellar-core.cfg` and indexes by IP, name, and public key; matched peers show a truncated key + `(Vn)` label
 - **Geo caching** — `_geo_cache` is a module-level dict; `geo_batch()` only fetches IPs not already cached
 - **Flag parsing** — manual `sys.argv` parsing; `-g` implies `-p`; `-i` accepts an optional next argument as the refresh interval
+- **Config precedence** — `config_refresh()` reads the config value; an explicit `-i SEC` argument overrides it
+- **Cycle timing** — `interactive_loop()` measures cycle duration and warns via `warn()` when it nears or exceeds `refresh_interval`, so a slow update doesn't silently push out the actual refresh cadence
+- **Persistent cbreak** — the tty is switched to cbreak once for the whole session (not reset to canonical between cycles); doing it per-cycle would flush unread input on the mode switch and leave the terminal line-buffered during `run_cycle()`, silently dropping keypresses (e.g. `q`) made while a cycle overruns `refresh_interval`
diff --git a/pi-stat b/pi-stat
index 05c4224..d0a3a5a 100755
--- a/pi-stat
+++ b/pi-stat
@@ -40,6 +40,13 @@ HAS_ZFS              = shutil.which("zpool") is not None
 CANDIDATE_CONTAINERS = ["mainnet", "testnet2", "testnet"]
 HORIZON_URL          = "http://localhost:31401"
 CFG_PATH             = os.path.join(os.path.dirname(os.path.realpath(__file__)), "stellar-core.cfg")
+DEFAULT_REFRESH      = 5
+REFRESH_WARN_RATIO   = 0.8  # warn if a cycle takes >= 80% of the refresh interval
+CONFIG_PATHS         = [
+    os.environ.get("PI_STAT_CONFIG"),
+    os.path.join(os.path.expanduser("~"), ".config", "pi-stat", "config.json"),
+    os.path.join(os.path.dirname(os.path.realpath(__file__)), "pi-stat.json"),
+]
 
 # --- Colors / Icons ---
 GREEN  = "\033[0;32m"
@@ -144,6 +151,33 @@ def geo_str(ip):
         return ", ".join(p for p in geo if p)
     return ""
 
+def load_config():
+    """Read the first existing config file (JSON object). Returns {} if none is usable."""
+    for path in CONFIG_PATHS:
+        if not path or not os.path.isfile(path):
+            continue
+        try:
+            with open(path, "r", encoding="utf-8") as fh:
+                data = json.load(fh)
+            if isinstance(data, dict):
+                return data
+            print(f"WARN: Config {path}: kein JSON-Objekt – wird ignoriert", file=sys.stderr)
+        except Exception as e:
+            print(f"WARN: Config {path} nicht lesbar: {e}", file=sys.stderr)
+        return {}
+    return {}
+
+
+def config_refresh(cfg):
+    """refresh_interval from config, clamped to >= 1 s; falls back to DEFAULT_REFRESH."""
+    val = cfg.get("refresh_interval", DEFAULT_REFRESH)
+    try:
+        return max(1, int(val))
+    except (TypeError, ValueError):
+        print(f"WARN: refresh_interval '{val}' ungültig – benutze {DEFAULT_REFRESH}s", file=sys.stderr)
+        return DEFAULT_REFRESH
+
+
 def load_validators(cfg_path):
     """Parse [[VALIDATORS]] sections, returning {ip_or_name: (index, public_key)}."""
     if not os.path.exists(cfg_path):
@@ -758,56 +792,75 @@ def interactive_loop(client, refresh_interval, peers_extended, geo_enabled, show
     traffic_extended = extended_traffic  # local, toggled with 'x'
 
     old_settings = termios.tcgetattr(sys.stdin)
+    # cbreak wird EINMAL für die gesamte Session gesetzt (nicht erst nach jedem
+    # run_cycle()). Andernfalls bleibt das Terminal während der Ausführung im
+    # zeilengepufferten Modus des alten old_settings, und das anschließende
+    # tty.setcbreak(..., TCSAFLUSH) verwirft dabei sogar noch ungelesene
+    # Eingaben – eine während einer langsamen Ausführung gedrückte Taste wie
+    # 'q' würde so nie ankommen.
+    tty.setcbreak(sys.stdin.fileno())
     try:
         while True:
+            cycle_start = time.monotonic()
             buf = io.StringIO()
             with contextlib.redirect_stdout(buf):
                 outbound_peers, container = run_cycle(
                     client, peers_extended, geo_enabled, show_ip, interactive=True,
                     extended_traffic=traffic_extended
                 )
+                cycle_duration = time.monotonic() - cycle_start
+                if cycle_duration >= refresh_interval:
+                    warn(f"Update dauerte {cycle_duration:.1f}s – "
+                         f"länger als das Intervall ({refresh_interval}s). "
+                         f"Intervall (refresh_interval) erhöhen.")
+                elif cycle_duration >= refresh_interval * REFRESH_WARN_RATIO:
+                    pct = cycle_duration / refresh_interval * 100
+                    warn(f"Update dauerte {cycle_duration:.1f}s "
+                         f"({pct:.0f}% des {refresh_interval}s-Intervalls) – knapp.")
             sys.stdout.write("\033[2J\033[H" + buf.getvalue())
             sys.stdout.flush()
 
-            deadline = time.monotonic() + refresh_interval
-            tty.setcbreak(sys.stdin.fileno())
-            try:
-                last_secs = -1
-                while True:
-                    remaining = max(0.0, deadline - time.monotonic())
-                    secs = int(remaining) + (1 if remaining % 1 > 0 else 0)
-                    if secs != last_secs:
-                        x_label = "RX/TX" if traffic_extended else "detail"
-                        text = f"  [d] Drop peer  [a] Drop all  [x] {x_label}  [q] Beenden  Refresh in {secs}s  "
-                        sys.stdout.write("\r" + text)
-                        sys.stdout.flush()
-                        last_secs = secs
+            # Timer läuft ab Beginn der Ausführung, nicht erst ab deren Ende –
+            # so verlängert die Update-Laufzeit nicht zusätzlich das Intervall.
+            deadline = cycle_start + refresh_interval
+            last_secs = -1
+            while True:
+                remaining = max(0.0, deadline - time.monotonic())
+                secs = int(remaining) + (1 if remaining % 1 > 0 else 0)
+                if secs != last_secs:
+                    x_label = "RX/TX" if traffic_extended else "detail"
+                    text = (f"  [d] Drop peer  [a] Drop all  [x] {x_label}  [q] Beenden  "
+                             f"Refresh in {secs}s  (Update: {cycle_duration:.1f}s)  ")
+                    sys.stdout.write("\r" + text)
+                    sys.stdout.flush()
+                    last_secs = secs
 
-                    if remaining <= 0:
-                        break
+                # Immer mindestens einmal (nicht-blockierend, wenn remaining
+                # bereits 0 ist) auf Eingabe prüfen – auch wenn die Deadline
+                # schon verstrichen ist, weil die Ausführung selbst länger als
+                # das Intervall dauerte. Sonst wird 'q' & Co. in diesem Fall
+                # nie abgefragt, da sofort in den nächsten Zyklus gesprungen würde.
+                timeout = min(remaining, 0.25) if remaining > 0 else 0
+                rlist, _, _ = select.select([sys.stdin], [], [], timeout)
+                if rlist:
+                    ch = sys.stdin.read(1)
+                    if ch in ('q', 'Q', '\x03', '\x04'):
+                        print()
+                        return
+                    elif ch in ('d', 'D') and outbound_peers and container:
+                        print()
+                        do_drop_workflow(outbound_peers, container)
+                        break  # trigger immediate refresh
+                    elif ch in ('a', 'A') and outbound_peers and container:
+                        print()
+                        drop_all_workflow(outbound_peers, container)
+                        break  # trigger immediate refresh
+                    elif ch in ('x', 'X'):
+                        traffic_extended = not traffic_extended
+                        break  # trigger immediate refresh
 
-                    rlist, _, _ = select.select([sys.stdin], [], [], min(remaining, 0.25))
-                    if rlist:
-                        ch = sys.stdin.read(1)
-                        if ch in ('q', 'Q', '\x03', '\x04'):
-                            termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_settings)
-                            print()
-                            return
-                        elif ch in ('d', 'D') and outbound_peers and container:
-                            termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_settings)
-                            print()
-                            do_drop_workflow(outbound_peers, container)
-                            break  # trigger immediate refresh
-                        elif ch in ('a', 'A') and outbound_peers and container:
-                            termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_settings)
-                            print()
-                            drop_all_workflow(outbound_peers, container)
-                            break  # trigger immediate refresh
-                        elif ch in ('x', 'X'):
-                            traffic_extended = not traffic_extended
-                            break  # trigger immediate refresh
-            finally:
-                termios.tcsetattr(sys.stdin, termios.TCSADRAIN, old_settings)
+                if remaining <= 0:
+                    break
 
     except KeyboardInterrupt:
         pass
@@ -829,9 +882,17 @@ Options:
   -s, --show-ip          Show IP column (hidden by default)
   -x, --extended         Full RX/TX/RX-rate/TX-rate columns (default: ratio only)
   -i [SEC], --interactive [SEC]
-                         Auto-refresh mode (default interval: 10 s)
+                         Auto-refresh mode (overrides the configured interval)
   -?, --help             Show this help and exit
 
+Config file (first match wins, JSON):
+  $PI_STAT_CONFIG
+  ~/.config/pi-stat/config.json
+  <script dir>/pi-stat.json
+
+  Keys:
+    refresh_interval   Auto-refresh interval in seconds (default: 5)
+
 Interactive keys:
   d   Drop one outbound peer
   a   Drop all outbound peers
@@ -853,7 +914,7 @@ def main():
     interactive       = "-i" in args or "--interactive" in args
     extended_traffic  = "-x" in args or "--extended" in args
 
-    refresh_interval = 10
+    refresh_interval = config_refresh(load_config())
     if interactive:
         for flag in ("-i", "--interactive"):
             if flag in args:
diff --git a/pi-stat.json b/pi-stat.json
new file mode 100644
index 0000000..b360a41
--- /dev/null
+++ b/pi-stat.json
@@ -0,0 +1,4 @@
+{
+  "_comment": "refresh_interval in Sekunden, min. 1 (Default: 5)",
+  "refresh_interval": 10
+  }