Don't upgrade to Mac OS X 10.9 Mavericks until you read this

Recently some Mac OS X 10.9 users have reported issues that JoyBidder places the bid too late, or didn't place bids at all in some cases. According to the log, JoyBidder was forced into sleep/standby mode frequently even with power management option is set to never sleep. JoyBidder does have a secondary thread/process which will restart the main thread if it is found idle for extended time, h
however, some of the sniping bids in between will be delayed.

It is suspected that the issue is caused by the "app nap" feature introduced in Mac OS X 10.9 Mavericks, which will put apps into sleep mode regardless of the power management setting. This obviously doesn't work well with apps that need to be running at background all the time, for example, eBay Auction Sniper application.

Here is extra information and a proposed solution. 
http://www.tekrevue.com/tip/disable-app-nap-os-x-mavericks/

If you haven't upgraded yet, please hold, until this above proposed solution have been verified, or you can try it yourself, and let me know if it fixes the problem.