Detect and warn slow Debug implementations for Message

Cargo.lock

@@ -2453,6 +2453,7 @@ version = "0.14.0-dev"
 dependencies = [
  "iced_beacon",
  "iced_core",
+ "log",
 ]
 
 [[package]]

debug/Cargo.toml

@@ -15,6 +15,7 @@ enable = ["dep:iced_beacon"]
 
 [dependencies]
 iced_core.workspace = true
+log.workspace = true
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
 iced_beacon.workspace = true

debug/src/lib.rs

@@ -135,7 +135,16 @@ mod internal {
 
     pub fn update(message: &impl std::fmt::Debug) -> Span {
         let span = span(span::Stage::Update);
+
+        let start = Instant::now();
         let message = format!("{message:?}");
+        let elapsed = start.elapsed();
+
+        if elapsed.as_millis() >= 1 {
+            log::warn!(
+                "Slow `Debug` implementation of `Message` (took {elapsed:?})!"
+            );
+        }
 
         BEACON.log(client::Event::MessageLogged(if message.len() > 49 {
             format!("{}...", &message[..49])