Visual studio startup and debugging. Source: https://youtu.be/GC-0tCy4P1U
For example back then they did not index files at startup since there was no function for that (like "find references"). These days IDEs provide a lot of "intelligence" and static analysis for which you need memory, a lot of reads and processing.
So yeah, I guess VS got slower but it's because it's now doing much more (useful) things.