Reproduction steps:
1. Open the attached “Slow UIToolkit” project
2. Build and run the Player (File > Build And Run)
3. Press in the top left corner
4. In the opened window, tick the “Show FPS Counter” checkbox
5. Close the window by tapping outside of it
6. Press the button with a star inside
7. Observe the fps counter in the top left

Expected result: The FPS does not drop
Actual result: The FPS drops significantly

Reproducible with: 2022.3.23f1, 6000.0.0b14
Could not test with: 2021.3.37f1 (Multiple “error CS0246: The type or namespace name 'TextureImporterSwizzle' could not be found” compilation errors), 2023.2.18f1 (Multiple “error CS1069: The type name 'EventProvider' could not be found in the namespace 'UnityEngine.InputForUI'.” compilation errors)

Reproducible environment: MacOS Sonoma 14.3.1 (Intel), (M1) (user’s)
Not reproducible environment: No other environment tested

Reproducible with these devices:
VLNQA00057, Htc One M9+ (HTC_M9pw), Android 6.0, CPU: MediaTek Helio X10 MT6795T, GPU: PowerVR Rogue G6200
VLNQA00146, Htc 10 (HTC 10), Android 7.0, CPU: Snapdragon 820 MSM8996, GPU: Adreno (TM) 530
Samsung Galaxy A3 2016 SM-A310F (Mali T-720) => 24 to 16 fps

Not reproducible with these devices:
VLNQA00175, Samsung Galaxy Note9 (SM-N960F), Android 10, CPU: Exynos 9 (9810), GPU: Mali-G72
VLNQA00519, Google Pixel 4 (Pixel 4), Android 12, CPU: Snapdragon 855 SM8150, GPU: Adreno (TM) 640
VLNQA00372, Samsung SM-G991U (SM-G991U), Android 12, CPU: Snapdragon 888, GPU: Adreno (TM) 660

Notes:
- Not reproducible on MacOS Sonoma 14.3.1 (Intel) (Buildtime, Runtime), iOS devices
- With the 6000.0.0b14 version, the Htc One M9+ device could not be tested due to the application crashing on launch