The highly-anticipated "Batman: Arkham Knight" video game went on sale on Tuesday after a delay but some users have already reported problems with the PC version of the title. The game was originally scheduled for release in October but was pushed back when developer Rocksteady Studios needed more time. But it seems that 8 months were not enough for the developers in order to patch thew game's bugs, at least in the version for PC. Users have been complaining on Twitter and gaming forums about framerate issues.

Rocksteady said the problem was being looked at.

"We're aware that some users are reporting performance issues on PC," Rocksteady tweeted. "We take this very seriously & we're investigating."