The mouse enter/leave handling has been optimized and should run smoothly on most modern computers and devices. It currently uses JavaScript animations but will likely get updated to make use of CSS3 animations in the future.
Try some of the following tips:
- Reduce the amount of animated elements, for example use a fixed caption style or just the fade effect.
- Disable the Overlay or the Special effects.
- Turn off the animation by setting General tab > Animation speed to 0. You can keep the overlay and special effects this way, but the transition will be instant.
- Decrease the General tab > Target row height value.
- If you have lots of small thumbnails, disable the captions as they get too small. This helps reduce animated elements.
- Try restarting your browser as it might be suffering due to the amount of tabs you opened during its run, consuming too much memory.
- Close Flash or HD videos playing in the background.
- Close any browser debugger tools because they slow animations when opened.
If your concern is primarily mobile devices, even up to a point where they might crash, then also check out The browser crashes or closes on my older iPhone or iPad.