Yes, a caching plugin would definitely help out there! Your site was featured in the last webdesigner depot newsletter (which has around 150K subsribers I think) and when I clicked the link I could not reach your site for 5 minutes...
Have you had a look at the W3 Total Cache plugin already? This drastically speeds up sites when configured correctly.
I'm wondering how you manage to constantly get so many up votes for your projects (besides creating super quality content of course). Any tips on this?
Btw: I love the toolbox, super awesome site! It seems to be a little slow for me though, are you hosting this on a shared server?