I still wasn’t able to reproduce this issue…
I use like 10 Chrome tabs at the same time with Makeroid Builder, GitKraken, Visual Studio Code, and two terminals, and I couldn’t detect any lag on Makeroid with projects with more than 1k blocks 
And all of this on my laptop which has a 500GB HDD, 4GBDDR3 + 4GB of RAM, i5 6th Gen up to 2.8Ghz…