diff --git a/test/AtomShell/window.jl b/test/AtomShell/window.jl
index 6286d39..644bba5 100644
--- a/test/AtomShell/window.jl
+++ b/test/AtomShell/window.jl
@@ -8,3 +8,12 @@ using Test
     size(w, 200,200)
     @test size(w) == [200,200]
 end
+
+@testset "async" begin
+    # Test that async Window() creation is faster than synchronous creation.
+    # (Repeat the test a few times, just to be sure it's consistent.)
+    for _ in 1:5
+        (@timed Window(Blink.@d(:show => false), async=true))[2] <
+         (@timed Window(Blink.@d(:show => false), async=false))[2]
+    end
+end