Improve scrolling performance for sticky headers
Improve scrolling performance for sticky headers

The layout updates are anecdotal based on devtools flagging the values which are "changing" even if they aren't.  The scrolling feels better with this as well, though this might be placebo. 
matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk,matrix-org/matrix-react-sdk