Ask HN: Which IDE handles very large projects the best?

Visual Studio

Agreed. The Solution Explorer is extremely easy to navigate and the search function is my new best friend (Ctrl + ;). My only grip is that the icons were a lot easier to tell apart in 2010, but I've gotten over that in time.

Additionally, I've had no problems with 30+ large projects in a solution.

Curious regarding which IDE's and how many files.

Split code into a number of subproject.

Not an IDE, but vim with ctags is an excellent combination.