diff --git a/README.md b/README.md
index b1f8bf0..c0fa69e 100644
--- a/README.md
+++ b/README.md
@@ -34,8 +34,9 @@ make PREFIX=/usr install # overwrites existing udev libraries if any
 TODO
 ----
 
-* [ ] speed up performance
+* [ ] speed up udev_enumerate_scan_devices()
   - [x] threads
   - [ ] deferred plugging via udev_monitor_receive_device()
+  - ~~[ ] caching~~ impossible to implement
 * [ ] implement hotplugging support
 * [x] remove [dirty hack](https://github.com/illiliti/libudev-zero/blob/e76f9b282442505bd6b0b08b411679aae1581fa5/udev_device.c#L383). use ioctl()