diff --git a/Cargo.lock b/Cargo.lock
index 55a1d67..22360fd 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1653,6 +1653,7 @@ dependencies = [
  "tokio",
  "tracing",
  "tracing-subscriber",
+ "uom",
 ]
 
 [[package]]
diff --git a/crates/ptth_file_server_bin/Cargo.toml b/crates/ptth_file_server_bin/Cargo.toml
index af3cf68..8d91c39 100644
--- a/crates/ptth_file_server_bin/Cargo.toml
+++ b/crates/ptth_file_server_bin/Cargo.toml
@@ -18,6 +18,7 @@ structopt = "0.3.20"
 tokio = { version = "0.2.22", features = ["full"] }
 tracing = "0.1.21"
 tracing-subscriber = "0.2.15"
+uom = "0.30.0"
 
 ptth_core = { path = "../ptth_core" }
 ptth_server = { path = "../ptth_server" }
diff --git a/crates/ptth_file_server_bin/src/main.rs b/crates/ptth_file_server_bin/src/main.rs
index 9ae3f47..b92d6e9 100644
--- a/crates/ptth_file_server_bin/src/main.rs
+++ b/crates/ptth_file_server_bin/src/main.rs
@@ -97,24 +97,46 @@ async fn main () -> Result <(), anyhow::Error> {
 		config_file.name.unwrap_or_else (|| "PTTH File Server".to_string ())
 	);
 	
-	let metrics_gauges = Arc::new (ArcSwap::default ());
+	let metrics_interval = Arc::new (ArcSwap::default ());
 	
-	let gauge_writer = Arc::clone (&metrics_gauges);
+	let interval_writer = Arc::clone (&metrics_interval);
 	
 	tokio::spawn (async move {
-		let mut interval = tokio::time::interval (std::time::Duration::from_secs (2));
+		use std::time::Duration;
+		
+		use uom::si::ratio::percent;
+		
+		let mut interval = tokio::time::interval (Duration::from_secs (60));
+		
+		let mut counter = 0_u64;
+		let mut next_10_time = counter;
+		let mut metrics_at_last_10: Arc <Option <metrics::Interval>> = Arc::new (None);
+		
 		loop {
 			interval.tick ().await;
 			
-			let new_gauges = match file_server::metrics::Gauges::new ().await {
+			let new_interval_metrics = match file_server::metrics::Interval::new ().await {
 				Err (e) => {
-					error! ("Failed to update gauge metrics: {:?}", e);
+					error! ("Failed to update interval metrics: {:?}", e);
 					continue;
 				},
 				Ok (x) => x,
 			};
-			let new_gauges = Arc::new (Some (new_gauges));
-			gauge_writer.store (new_gauges);
+			let new_interval_metrics = Arc::new (Some (new_interval_metrics));
+			
+			if counter >= next_10_time {
+				if let (Some (old), Some (new)) = (&*metrics_at_last_10, &*new_interval_metrics) {
+					let diff = new.cpu_usage.clone () - old.cpu_usage.clone ();
+					trace! ("CPU usage: {}%", diff.get::<percent> ());
+				}
+				
+				next_10_time += 1;
+				metrics_at_last_10 = new_interval_metrics.clone ();
+			}
+			
+			interval_writer.store (new_interval_metrics);
+			counter += 1;
+			//trace! ("interval metrics 1");
 		}
 	});
 	
@@ -124,7 +146,7 @@ async fn main () -> Result <(), anyhow::Error> {
 		},
 		handlebars,
 		metrics_startup,
-		metrics_gauges,
+		metrics_interval,
 		hidden_path: Some (path),
 	});
 	
diff --git a/crates/ptth_server/src/file_server/html.rs b/crates/ptth_server/src/file_server/html.rs
index 0a1fdfa..afdc022 100644
--- a/crates/ptth_server/src/file_server/html.rs
+++ b/crates/ptth_server/src/file_server/html.rs
@@ -52,12 +52,12 @@ pub async fn serve_root (
 	#[derive (Serialize)]
 	struct RootHtml <'a> {
 		metrics_startup: &'a metrics::Startup,
-		metrics_gauges: &'a Option <metrics::Gauges>,
+		metrics_interval: &'a Option <metrics::Interval>,
 	}
 	
 	let params = RootHtml {
 		metrics_startup: &state.metrics_startup,
-		metrics_gauges: &**state.metrics_gauges.load (),
+		metrics_interval: &**state.metrics_interval.load (),
 	};
 	
 	let s = state.handlebars.render ("file_server_root", &params)?;
diff --git a/crates/ptth_server/src/file_server/metrics.rs b/crates/ptth_server/src/file_server/metrics.rs
index f5666f1..6dd7a9d 100644
--- a/crates/ptth_server/src/file_server/metrics.rs
+++ b/crates/ptth_server/src/file_server/metrics.rs
@@ -2,15 +2,10 @@ use chrono::{DateTime, Utc};
 use tracing::debug;
 use ulid::Ulid;
 
-fn serialize_ulid <S: serde::Serializer> (t: &Ulid, s: S) 
--> Result <S::Ok, S::Error> 
-{
-	let t = t.to_string ();
-	s.serialize_str (&t)
-}
-
-// Instance metrics are captured when the ptth_server process starts.
-// They don't change after that.
+// Metrics are named for when they're updated:
+// - Startup (Once, when the server state is initialized)
+// - Interval (About once per minute)
+// - Events (When a request is processed)
 
 #[derive (Debug, serde::Serialize)]
 pub struct Startup {
@@ -33,23 +28,45 @@ pub struct Startup {
 	pub startup_utc: DateTime <Utc>,
 }
 
-// Gauges are things we instananeously measure on a fixed interval.
-// They are not read back and accumulated like counters.
-
 #[derive (Debug, serde::Serialize)]
-pub struct Gauges {
+pub struct Interval {
 	pub utc: DateTime <Utc>,
 	pub rss_mib: u64,
 	
-	// What's the difference?
-	pub cpu_time_user: f64,
-	pub cpu_time_system: f64,
-	
 	#[serde (skip)]
 	pub cpu_usage: heim::process::CpuUsage,
 }
 
-impl Gauges {
+pub struct Events {
+	
+}
+
+impl Startup {
+	#[must_use]
+	pub fn new (server_name: String) -> Self
+	{
+		let x = Self {
+			machine_id: get_machine_id (),
+			git_version: None,
+			server_name,
+			instance_id: ulid::Ulid::new (),
+			startup_utc: Utc::now (),
+		};
+		
+		debug! ("metrics at startup: {:?}", x);
+		
+		x
+	}
+}
+
+fn serialize_ulid <S: serde::Serializer> (t: &Ulid, s: S) 
+-> Result <S::Ok, S::Error> 
+{
+	let t = t.to_string ();
+	s.serialize_str (&t)
+}
+
+impl Interval {
 	pub async fn new () -> Result <Self, super::FileServerError> {
 		use tokio::join;
 		use heim::process;
@@ -61,33 +78,22 @@ impl Gauges {
 		
 		let our_process = process::current ().await?;
 		
-		let cpu_time = our_process.cpu_time ();
 		let cpu_usage = our_process.cpu_usage ();
 		
-		let (cpu_time, cpu_usage) = join! (
-			cpu_time,
+		let (cpu_usage, mem) = join! {
 			cpu_usage,
-		);
-		
-		let cpu_time = cpu_time?;
-		
-		let cpu_time_user = cpu_time.user ().get::<second> ();
-		let cpu_time_system = cpu_time.system ().get::<second> ();
+			our_process.memory ()
+		};
 		let cpu_usage = cpu_usage?;
-		
-		let mem = our_process.memory ().await?;
+		let mem = mem?;
 		let rss_mib = mem.rss ().get::<mebibyte> ();
 		
-		let x = Gauges {
+		let x = Self {
 			utc: Utc::now (),
 			rss_mib,
-			cpu_time_user,
-			cpu_time_system,
 			cpu_usage,
 		};
 		
-		debug! ("metric gauges: {:?}", x);
-		
 		Ok (x)
 	}
 }
@@ -110,24 +116,6 @@ fn get_machine_id () -> Option <String> {
 	Some (s)
 }
 
-impl Startup {
-	#[must_use]
-	pub fn new (server_name: String) -> Self
-	{
-		let x = Self {
-			machine_id: get_machine_id (),
-			git_version: None,
-			server_name,
-			instance_id: ulid::Ulid::new (),
-			startup_utc: Utc::now (),
-		};
-		
-		debug! ("metrics at startup: {:?}", x);
-		
-		x
-	}
-}
-
 #[cfg (test)]
 mod tests {
 	use super::*;
diff --git a/crates/ptth_server/src/file_server/mod.rs b/crates/ptth_server/src/file_server/mod.rs
index 3817ee4..78468a0 100644
--- a/crates/ptth_server/src/file_server/mod.rs
+++ b/crates/ptth_server/src/file_server/mod.rs
@@ -59,7 +59,7 @@ pub struct State {
 	pub config: Config,
 	pub handlebars: handlebars::Handlebars <'static>,
 	pub metrics_startup: metrics::Startup,
-	pub metrics_gauges: Arc <ArcSwap <Option <metrics::Gauges>>>,
+	pub metrics_interval: Arc <ArcSwap <Option <metrics::Interval>>>,
 	pub hidden_path: Option <PathBuf>,
 }
 
diff --git a/crates/ptth_server/src/lib.rs b/crates/ptth_server/src/lib.rs
index 56eac6b..64d5eff 100644
--- a/crates/ptth_server/src/lib.rs
+++ b/crates/ptth_server/src/lib.rs
@@ -201,7 +201,7 @@ pub async fn run_server (
 	let handlebars = file_server::load_templates (&asset_root)?;
 	
 	let metrics_startup = file_server::metrics::Startup::new (config_file.name);
-	let metrics_gauges = Arc::new (ArcSwap::default ());
+	let metrics_interval = Arc::new (ArcSwap::default ());
 	
 	let state = Arc::new (State {
 		file_server: file_server::State {
@@ -210,7 +210,7 @@ pub async fn run_server (
 			},
 			handlebars,
 			metrics_startup,
-			metrics_gauges,
+			metrics_interval,
 			hidden_path,
 		},
 		config: Config {
diff --git a/handlebars/server/file_server_root.html b/handlebars/server/file_server_root.html
index e852ecc..7cd63df 100644
--- a/handlebars/server/file_server_root.html
+++ b/handlebars/server/file_server_root.html
@@ -24,7 +24,7 @@
 
 <h2>Gauges</h2>
 
-<p>RSS MiB: {{metrics_gauges.rss_mib}}</p>
+<p>RSS MiB: {{metrics_interval.rss_mib}}</p>
 
 <div class="entry_list">