Hello
We are still using v3 and this may be a stupid question but specifically is the speed of findCell increased in the lastest version?
There were no critical changes in the findCell logic that improved the performance of the method.
But the total performance of the grid was improved, so you may check if it help in your situation.
Also you may provide with a complete demo/share with a demo link, so your page could be checked for suggestion about improving the performance.