I have problem with my hardware running at half speed.
It is a ATmega88 and it should run with the internal oscullator. Before I changed the fuse bits so it should run at the internal oscillator (this is default so it do not need to be changed) and without the CLKDIV8. Now I changed it so the code changes the CKDIV to DIV0 but now the clock runs at half speed for some reason. I do calibrate the OSCCAL register using an external 32kHz crystal but I havent changed anything there. Also I do not think it i possible to set the clock so low. I have tried to set my UART speed to double speed and if I do so it works so it is more or less exactly half the speed and that makes me think it is some simple setting I have forgot.
I have checked in Studio that the CKDIV is beeing set to 0.