Hard drive speed is important to overall Visual Studio performance. Scott Guthrie touches on it well in this post:
Multi-core CPUs on machines have gotten fast enough over the past few years that in most common application scenarios you don't usually end up blocking on available processor capacity in your machine.
When you are doing development with Visual Studio you end up reading/writing a lot of files, and spend a large amount of time doing disk I/O activity. Large projects and solutions might have hundreds (or thousands) of source files (including images, css, pages, user controls, etc). When you open a project Visual Studio needs to read and parse all source files in it so as to provide intellisense. When you are enlisted in source control and check out a file you are updating files and timestamps on disk. When you do a compilation of a solution, Visual Studio will check for updated assemblies from multiple disk path locations, write out multiple new assemblies to disk when the compilation is done, as well as persist .pdb debugger symbol files on disk with them (all as separate file save operations). When you attach a debugger to a process (the default behavior when you press F5 to run an application), Visual Studio then needs to search and load the debugger symbols of all assemblies and DLLs for the application so as to setup breakpoints.
Visual Studio Blog recommends using a SSD:
Hard drive type matters!
And here is another trick to make solution
load even faster. Visual Studio telemetry shows that machines with an
SSD storage load solutions 2-3 times faster than a regular hard drive.
As such, we strongly recommend considering an upgrade to SSD if you
are using a regular hard drive. While ideally Windows, Visual Studio,
and your solution would all be contained on an SSD for the maximum
impact, having Windows installed on SSD will have a huge impact on
your solution load.