hellafast is pretty damned quick. It's not as fast as stupidfast, but it'll still smoke things that are just "fast". e.g., ASDL is hellafast, compared to a 56Kmodem.
Synonyms for hellafast
On this page, you will find 30 slang terms related to hellafast. Some of the top words include: DWDM, 56ghey, right quick, speed dial, P D Q, and 25 more.