Is this happening to all your apps? Can you try with a new one? Also, what is your os and powerapps version? I don't have your issue with my desktop studio.
I strongly recommend using the Web client to create/modify your apps. I use it on Chrome and I have never had any performance issues. Over the last several months the web client got very stable and I rarely get session timeouts which are not as devastating as before due to the auto save function.
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