Depending on the system EuiTooltip caused a performance issue in Kibana Discover. The attached Gifs show a significant higher CPU usage by hovering the Elements containing a EuiTooltip it in Chrome 83, MacOs 10.14.6. While it wasn't that bad on my MacBook Pro (just when moving around the mouse like crazy), it seems to have a significant higher performance impact on Windows based machines (also when not moving around the mouse quickly), also Linux based system reported a much higher impact. Here is the original issue that reported it:

elastic/kibana#67732

Here the PR replacing EuiTooltip:

elastic/kibana#68280

Sidebar elements with EuiTooltip

Sidebar elements with native tooltip with title attribute