diff --git a/agent/fc_agent/app.py b/agent/fc_agent/app.py
index f93b9fe..c7fb992 100644
--- a/agent/fc_agent/app.py
+++ b/agent/fc_agent/app.py
@@ -75,9 +75,11 @@ _PAGE = """<!doctype html><html><head><meta charset=utf-8>
 <div class=row>
  workers
  <button class=step onclick=setc(-1)>−</button>
- <b id=conc style=margin:0+.5rem>1</b>
+ <input id=conc type=number min=1 value=1
+  style="width:3.5rem;font:700 16px system-ui;text-align:center;background:#222;color:#e8e8e8;border:1px solid #444;border-radius:6px;padding:.3rem"
+  onchange="setv(this.value)">
  <button class=step onclick=setc(1)>+</button>
- <span class=cap style=color:#9aa>(more = faster + more GPU)</span>
+ <span class=cap style=color:#9aa>(more = overlap I/O, fill the GPU) max <b id=capn>8</b></span>
 </div>
 <div class=row>
  <span class=stat><span class=n id=state>stopped</span><br>state</span>
@@ -89,16 +91,21 @@ _PAGE = """<!doctype html><html><head><meta charset=utf-8>
 <div class=bar><i id=gpubar style=width:0%></i></div>
 <div class=q id=queue></div>
 <script>
+ let CAP=8
  async function act(p){await fetch('/'+p,{method:'POST'});refresh()}
- async function setc(d){
-  const v=Math.max(1,Math.min(8,parseInt(conc.textContent||'1')+d))
+ function setc(d){ setv((parseInt(conc.value||'1'))+d) }
+ async function setv(v){
+  v=Math.max(1,Math.min(CAP,parseInt(v)||1)); conc.value=v
   await fetch('/concurrency',{method:'POST',headers:{'Content-Type':'application/json'},
    body:JSON.stringify({value:v})});refresh()
  }
  async function refresh(){
   const s=await (await fetch('/status')).json()
+  CAP=s.max_concurrency||8; capn.textContent=CAP
   state.textContent=s.state; active.textContent=s.active; done.textContent=s.processed
-  err.textContent=s.errors; conc.textContent=s.concurrency; fc.textContent=s.fc_url
+  err.textContent=s.errors; fc.textContent=s.fc_url
+  if(document.activeElement!==conc) conc.value=s.concurrency
+  conc.max=CAP
   cfg.textContent=s.configured?'set':'MISSING'
   if(s.gpu){
    gpu.textContent=`GPU — ${s.gpu.util_pct}% util · VRAM ${s.gpu.mem_used_mb}/${s.gpu.mem_total_mb} MB · ${s.gpu.temp_c}°C`
diff --git a/agent/fc_agent/client.py b/agent/fc_agent/client.py
index bf8e8d5..7003bcc 100644
--- a/agent/fc_agent/client.py
+++ b/agent/fc_agent/client.py
@@ -4,6 +4,7 @@ The agent's ONLY contact with FC — lease/submit/heartbeat/fail + fetch image
 bytes, all over HTTP with the bearer token. No DB/Redis.
 """
 import requests
+from requests.adapters import HTTPAdapter
 
 
 class FcClient:
@@ -12,6 +13,11 @@ class FcClient:
         self.agent_id = agent_id
         self.s = requests.Session()
         self.s.headers["Authorization"] = f"Bearer {token}"
+        # Many worker threads share this Session; the default pool (10) would
+        # throttle them + spam "connection pool is full". Size it for the cap.
+        adapter = HTTPAdapter(pool_connections=64, pool_maxsize=64)
+        self.s.mount("http://", adapter)
+        self.s.mount("https://", adapter)
 
     def lease(self, batch_size: int) -> list[dict]:
         r = self.s.post(
diff --git a/agent/fc_agent/worker.py b/agent/fc_agent/worker.py
index 64bc3f9..52a8d75 100644
--- a/agent/fc_agent/worker.py
+++ b/agent/fc_agent/worker.py
@@ -17,7 +17,10 @@ from .client import FcClient
 from .config import Config
 from .crops import crop_region
 
-MAX_CONCURRENCY = 8
+# Generous cap: the pipeline is usually I/O-bound (downloading + decoding images
+# over HTTP), so the GPU stays underused until many workers overlap that I/O.
+# Push it up while watching the GPU util + VRAM in the UI.
+MAX_CONCURRENCY = 32
 
 
 class _Slot:
@@ -74,6 +77,7 @@ class Worker:
             return {
                 "state": "running" if self._running else "stopped",
                 "concurrency": self._target,
+                "max_concurrency": MAX_CONCURRENCY,
                 "workers": len(self._slots),
                 "active": self._active,
                 "processed": self.processed,
