There's already a fix.
Use Lulzactiveq or performance governor. If you are on stock kernel,then you need an third-party app to do that task for you (change to performance gov. when camera is open).
EDIT: No one answered my question. Are all Kitkat ROMs using new GPU drivers from Official Sammy 4.3 ?
/* * Your warranty is now void. * * I am not responsible for bricked devices, dead SD cards, * thermonuclear war, or you getting fired because the alarm app failed. Please * do some research if you have any concerns about features included in this ROM * before flashing it! YOU are choosing to make these modifications, and if * you point the finger at me for messing up your device, I will laugh at you. Hard. A lot. */
If you chooses to use my unofficial build here, pls DO NOT post your issues and/or request support from the official cm10 thread. My builds contains yet-to-approved commits and MAY affect codeworkx's debugging process. Pls understand and I hope to get your support on this.
Latest official CWM recommended but not required.
1. Disable FAST DORMANCY if your telco doesn't support it. There is an app in Play Store called "FastDormancy Toggle" for i9300.