Yep, thats a bit issue with all Valve servers. Even the Source engine servers use only one thread to do their work.
About development of E[POD]bot, the project is not completely dead, because I'm still here to support the forum but no actual development has been done sinse years... So we can say it's almost dead.
About the high CPU usage. I know Podbot_mm is more CPU friendly and is still in active development. You can try it. Also be sure that the server doesn't have too much plugins overall. Remove everything you don't really need.