Hi,
I believe the default for MSAA to be set to 4 samples, which will have little impact on performance. Correction, as per the doc the default is 1 even when not called but I believe it to be 4 when enabled. Although, may be it is still 1 unless you set the samples. I’m not all too sure 
By any means, 4 samples doesn’t do much and I believe will have very tiny-mini incidence on performance.
I opened the scene on my legacy test rig (a 2009 mac-pro with 1GB medium range GPU).
With MSAA set to 4-samples I get about the same FPS as with 1 sample (around 25 fps). However, pushing MSAA to 64 samples, performance drops to ~15fps.
Edit: and then may be you’ll want to add FXAA ? MSAA is not the outmost for antialising (my opinion only, of course).
https://doc.babylonjs.com/features/featuresDeepDive/postProcesses/defaultRenderingPipeline#antialiasing