diff --git a/src/broadcaster.zig b/src/broadcaster.zig
index ca02d96..4cac682 100644
--- a/src/broadcaster.zig
+++ b/src/broadcaster.zig
@@ -683,8 +683,13 @@ fn appendProcMetrics(w: anytype) void {
     } else |_| {}
 
     // glibc malloc arena stats — distinguishes in-use heap from fragmentation
-    // mallinfo uses int fields (cap at 2 GiB) but sufficient for trend analysis
+    // mallinfo returns c_int (i32) fields which overflow at 2 GiB; bitcast to u32
+    // extends useful range to 4 GiB per field
     const mi = malloc_h.mallinfo();
+    const arena: u64 = @as(u32, @bitCast(mi.arena));
+    const in_use: u64 = @as(u32, @bitCast(mi.uordblks));
+    const free_bytes: u64 = @as(u32, @bitCast(mi.fordblks));
+    const mmap_bytes: u64 = @as(u32, @bitCast(mi.hblkhd));
     std.fmt.format(w,
         \\# TYPE relay_malloc_arena_bytes gauge
         \\# HELP relay_malloc_arena_bytes total bytes claimed from OS by malloc
@@ -702,7 +707,7 @@ fn appendProcMetrics(w: anytype) void {
         \\# HELP relay_malloc_mmap_bytes bytes allocated via mmap (large blocks)
         \\relay_malloc_mmap_bytes {d}
         \\
-    , .{ mi.arena, mi.uordblks, mi.fordblks, mi.hblkhd }) catch {};
+    , .{ arena, in_use, free_bytes, mmap_bytes }) catch {};
 }
 
 const posix_vfs = @cImport(@cInclude("sys/statvfs.h"));
diff --git a/src/validator.zig b/src/validator.zig
index 3402c0c..9d40a1e 100644
--- a/src/validator.zig
+++ b/src/validator.zig
@@ -55,6 +55,8 @@ pub const Validator = struct {
     cache_mutex: std.Thread.Mutex = .{},
     // background resolve queue
     queue: std.ArrayListUnmanaged([]const u8) = .{},
+    // in-flight set — prevents duplicate DID entries in the queue
+    queued_set: std.StringHashMapUnmanaged(void) = .{},
     // migration validation queue
     migration_queue: std.ArrayListUnmanaged(MigrationCheck) = .{},
     queue_mutex: std.Thread.Mutex = .{},
@@ -65,6 +67,10 @@ pub const Validator = struct {
 
     const max_resolver_threads = 8;
     const default_resolver_threads = 4;
+    // process 1 migration check per N DID resolutions to prevent migration queue starvation
+    const migration_interleave_interval = 10;
+    // recreate http resolver after N resolutions to bound connection pool growth
+    const resolver_recycle_interval = 1000;
 
     pub fn init(allocator: Allocator, stats: *broadcaster.Stats) Validator {
         return initWithConfig(allocator, stats, .{});
@@ -100,6 +106,7 @@ pub const Validator = struct {
             self.allocator.free(did);
         }
         self.queue.deinit(self.allocator);
+        self.queued_set.deinit(self.allocator);
 
         // free migration queue
         for (self.migration_queue.items) |mc| {
@@ -387,10 +394,18 @@ pub const Validator = struct {
 
         self.queue_mutex.lock();
         defer self.queue_mutex.unlock();
+
+        // skip if already queued (prevents duplicate in-flight resolutions)
+        if (self.queued_set.contains(duped)) {
+            self.allocator.free(duped);
+            return;
+        }
+
         self.queue.append(self.allocator, duped) catch {
             self.allocator.free(duped);
             return;
         };
+        self.queued_set.put(self.allocator, duped, {}) catch {};
         self.queue_cond.signal();
     }
 
@@ -408,10 +423,11 @@ pub const Validator = struct {
                 while (self.queue.items.len == 0 and self.migration_queue.items.len == 0 and self.alive.load(.acquire)) {
                     self.queue_cond.timedWait(&self.queue_mutex, 1 * std.time.ns_per_s) catch {};
                 }
-                if (self.queue.items.len > 0) {
-                    did = self.queue.orderedRemove(0);
-                } else if (self.migration_queue.items.len > 0) {
+                if (self.migration_queue.items.len > 0 and (self.queue.items.len == 0 or resolve_count % migration_interleave_interval == 0)) {
                     migration = self.migration_queue.orderedRemove(0);
+                } else if (self.queue.items.len > 0) {
+                    did = self.queue.orderedRemove(0);
+                    _ = self.queued_set.remove(did.?);
                 }
             }
 
@@ -427,7 +443,7 @@ pub const Validator = struct {
 
                 // periodically recreate resolver to free accumulated http.Client state
                 resolve_count += 1;
-                if (resolve_count % 1000 == 0) {
+                if (resolve_count % resolver_recycle_interval == 0) {
                     resolver.deinit();
                     resolver = zat.DidResolver.init(self.allocator);
                 }