Installation does nothing other than creating some files on your machine. The only reason I would say is you may get out of space.

Check plugins in VS. Like browser link can slow down VS when enabled. Alloyt has nothing todo with VS though at mentioned. Is this happening when you run the project? 

It seems VS is behaving funny. (I'm not using Browser link)

Whatever I'm doing, creating a new folder, manage nuget packages or whatever it gets unresponsive for a few seconds.

This only happens to EPiServer applications created wit VS, File - New - Project - EPiServer project 

Every other EPiServer applications, ex cloned from Git make VS behave as expected.

Have you tried deleting the .vs folder (it's hidden)? Does it make any difference?

Check is there any updates available for visual studio, also EPiServer nuget package source (http://nuget.episerver.com/feed/packages.svc/) is configured properly. Try reinstalling episerver VS plugin.

Haven't noticed this at all I'm afraid. I would guess that something else is slowing it down. Resharper if you have a slow machine for instance. Love that btw but it sure loves my poor processor too...

I finally found the reason for the bad VS performance. My Alloy EPiserver projects for testing purpose were located at a network location folder.

Moving them to my C:\ disk resolved the VS performance problem.

Thank you for your feedback!

Ah yes! Slow disk is pure evil for VS :)