Alucard is hands down the best kernel for SGS4! Thank you OP for starting the thread!
I have different priorities than most users and the Alucard kernel with the flexibility provided by STweaks is just incredible.
I make light use of my phone during the day but I oftentimes play games till battery drain in the evening.
Particularly ShadowGun: DeadZone.
It's a demanding 3D shooter game where speed is a great advantage. I've suffered stutter since day 1 on my SGS4(T-Mobile). Interestingly my old phone - Nexus 4 was very fluid but had a slow touchscreen making gaming unpleasant in a different way. Since the SGS4 uses the newer generation Qualcomm SoC (Snapdragon 600 vs S4 Pro) I suspect that Samsung may be using slower Flash memory on the Galaxy S4, at least the M919 T-Mobile variant or maybe just my particular device.
I've tried every tweak there is but so far the only thing that has helped eliminate stutter is using a "deadline" IO scheduler on the Internal Flash. If I understand correctly deadline ensures time slots which helps synchronize repeating events such as video.
Other thoughts on optimizations:
Each SoCs is made differently but generally you should be able to undervolt -10%. STweaks plays it safe and allows undervolting only about -5% from stock. Go ahead and pull your CPU Voltage sliders all the way to the left!
Note that at 378kHz the CPU can run @825
mV. 702kHz needs 850mV. 3% more power will allow you to finish your task almost twice as fast!!!
It doesn't makes sense to run your phone below 702kHz ever. Be aware that this logic only plays true if you have proper cooling. The battery drains much faster as heat builds up. I'm not a fan of CPU speed scaling because it only helps save a little power when there is no activity, for example during reading. Limiting the max CPU frequency to a point where the SoC can cool itself efficiently is another strategy for power saving. I find that my phone is still very fast @ 1.3GHz while higher frequency steps can make it very hot. Thermal protection is very bad for performance so ideally you never want it to kick in. I think the 702-1350kHz window is the sweet spot for performance/battery as it gives you almost double the performance at about 10% extra power.
I can play demanding 3D games with the GPU @128k
Hz without problems. However I see no heat issues with the GPU at higher clock rates so I have it at:
GPU GOVERNOR performance
GPU MAX FREQ 320
GPU MIN FREQ 320
GPU THERMAL 450