io/router: improve benchmark by trying multiple sizes

This commit improves the usefulness of the benchmark by automatically
measuring event processing times with a range of values for the complexity
of the UI.

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

io/router/pointer_test.go

@@ -3,6 +3,7 @@
 package router
 
 import (
+	"fmt"
 	"image"
 	"testing"
 
@@ -452,7 +453,11 @@ func BenchmarkRouterAdd(b *testing.B) {
 	// evaluate performance for. Typical values for the example applications
 	// are 1-3, though checking highers values helps evaluate performance for
 	// more complex applications.
-	const handlerCount = 3
+	const startingHandlerCount = 3
+	const maxHandlerCount = 100
+	for i := startingHandlerCount; i < maxHandlerCount; i *= 3 {
+		handlerCount := i
+		b.Run(fmt.Sprintf("%d-handlers", i), func(b *testing.B) {
 			handlers := make([]event.Key, handlerCount)
 			for i := 0; i < handlerCount; i++ {
 				h := new(int)
@@ -485,4 +490,6 @@ func BenchmarkRouterAdd(b *testing.B) {
 					},
 				)
 			}
+		})
+	}
 }