I have noticed that with all my projects with a .git in the project folder, Rstudio is extremely slow - it will take minutes to become operational; visualising the content of the different windows or executing simple commands in console. If I remove the .git file and reload the project, it goes back to normal.
Ubuntu 18.04.3 LTS
R version 3.6.1 (2019-07-05) -- "Action of the Toes"
Copyright (C) 2019 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)
RStudio version 1.2.5019 (Elderflower)