diff --git a/booru_viewer/core/api/base.py b/booru_viewer/core/api/base.py
index 62c3fd7..be3b0b4 100644
--- a/booru_viewer/core/api/base.py
+++ b/booru_viewer/core/api/base.py
@@ -37,6 +37,9 @@ class BooruClient(ABC):
 
     api_type: str = ""
 
+    # Shared client across all BooruClient instances for connection reuse
+    _shared_client: httpx.AsyncClient | None = None
+
     def __init__(
         self,
         base_url: str,
@@ -46,26 +49,25 @@ class BooruClient(ABC):
         self.base_url = base_url.rstrip("/")
         self.api_key = api_key
         self.api_user = api_user
-        self._client: httpx.AsyncClient | None = None
 
     @property
     def client(self) -> httpx.AsyncClient:
-        if self._client is None or self._client.is_closed:
-            self._client = httpx.AsyncClient(
+        if BooruClient._shared_client is None or BooruClient._shared_client.is_closed:
+            BooruClient._shared_client = httpx.AsyncClient(
                 headers={"User-Agent": USER_AGENT},
                 follow_redirects=True,
                 timeout=20.0,
                 event_hooks={"request": [self._log_request]},
+                limits=httpx.Limits(max_connections=10, max_keepalive_connections=5),
             )
-        return self._client
+        return BooruClient._shared_client
 
     @staticmethod
     async def _log_request(request: httpx.Request) -> None:
         log_connection(str(request.url))
 
     async def close(self) -> None:
-        if self._client and not self._client.is_closed:
-            await self._client.aclose()
+        pass  # shared client stays open
 
     @abstractmethod
     async def search(
diff --git a/booru_viewer/core/api/detect.py b/booru_viewer/core/api/detect.py
index c34c995..418be37 100644
--- a/booru_viewer/core/api/detect.py
+++ b/booru_viewer/core/api/detect.py
@@ -23,11 +23,17 @@ async def detect_site_type(
     """
     url = url.rstrip("/")
 
-    async with httpx.AsyncClient(
-        headers={"User-Agent": USER_AGENT},
-        follow_redirects=True,
-        timeout=10.0,
-    ) as client:
+    from .base import BooruClient as _BC
+    # Reuse shared client for site detection
+    if _BC._shared_client is None or _BC._shared_client.is_closed:
+        _BC._shared_client = httpx.AsyncClient(
+            headers={"User-Agent": USER_AGENT},
+            follow_redirects=True,
+            timeout=20.0,
+            limits=httpx.Limits(max_connections=10, max_keepalive_connections=5),
+        )
+    client = _BC._shared_client
+    if True:  # keep indent level
         # Try Danbooru / e621 first — /posts.json is a definitive endpoint
         try:
             params: dict = {"limit": 1}
diff --git a/booru_viewer/core/api/e621.py b/booru_viewer/core/api/e621.py
index b465ea1..b7975fe 100644
--- a/booru_viewer/core/api/e621.py
+++ b/booru_viewer/core/api/e621.py
@@ -15,19 +15,23 @@ log = logging.getLogger("booru")
 class E621Client(BooruClient):
     api_type = "e621"
 
+    _e621_client: httpx.AsyncClient | None = None
+    _e621_ua: str = ""
+
     @property
     def client(self) -> httpx.AsyncClient:
-        if self._client is None or self._client.is_closed:
-            # e621 requires a descriptive User-Agent with username
-            ua = USER_AGENT
-            if self.api_user:
-                ua = f"{USER_AGENT} (by {self.api_user} on e621)"
-            self._client = httpx.AsyncClient(
+        ua = USER_AGENT
+        if self.api_user:
+            ua = f"{USER_AGENT} (by {self.api_user} on e621)"
+        if E621Client._e621_client is None or E621Client._e621_client.is_closed or E621Client._e621_ua != ua:
+            E621Client._e621_ua = ua
+            E621Client._e621_client = httpx.AsyncClient(
                 headers={"User-Agent": ua},
                 follow_redirects=True,
                 timeout=20.0,
+                limits=httpx.Limits(max_connections=10, max_keepalive_connections=5),
             )
-        return self._client
+        return E621Client._e621_client
 
     async def search(
         self, tags: str = "", page: int = 1, limit: int = DEFAULT_PAGE_SIZE