As some of you might know, Notes/Domino in Eclipse contains a lot of files. I believe it was somewhere around 35 000 for Notes/Sametime/Domino Designer 8.5.1.
Random access time (the time it takes to find/access a random file) is where mechanical disks probably are at it's weakest. This is especially noticable when you want to access a lot of files "at once", like when you want to start Notes cold (not started since booting the computer).
When the first SSDs came out, the test results were lousy. After reading about ten tests the initial months after SSDs became commercial, I more or less forgot about SSDs.
Then I read this. Cold starting Lotus Notes in 4 seconds?!?!
To be certain, I nagged my boss into testing out an SSD at work. I ended up with a Corsair, which has good write and read speeds. I don't think I'm exaggerating when I say that it felt like a new computer. I'm not sure my work computer starts Notes below five seconds (Core 2 Duo/1.7GHz), but it's well below 10 seconds.
What probably made me the most happiest is that during the weekly antivirus scan, I could work as normal. With the mechanical disk, it felt like working on a computer from the 20th century.
Then I decided it was time to get an SSD for my desktop computer at home. After reading a test at tomshardware.com, I decided on a 80GB Intel X25M G2. It has decent write speed, and great read speed.
I'm happy I decided on that disk after reading this performance comparison (at the time of writing, Intel X25M G2 at the top).
When SSDs become as cheap as mechanical drives, it's going to do a lot for servers worldwide.
If you're still not convinced (10 000 RPM IDE disk vs SSD):