[MediaPi]

If its working so far then they are good settings. I would add

h264_freq=275
isp_freq=1
v3d_freq=275

(h264 will be exactly half core which is good for arm, I believe)

take out temp_limit (not needed)

I tried to disable splash once to see if it will get faster boot load. I remeber it was a disastrous for some reason. I would take it out

take out avoid_pwm_pll=1 to. I did some testing and if you include this setting. you dont have control over h264, isp, v3d. I believe they stick with just one setting

also not sure why you got boot_delay get rid of that

and include disable_pvt=1

also add initial_turbo=60


force_turbo=1
gpu_mem=320
disable_overscan=1
arm_freq=1100
core_freq=550
sdram_freq=600
over_voltage=8
hdmi_force_hotplug=1
h264_freq=275
isp_freq=1
v3d_freq=275
disable_pvt=1
initial_turbo=60

see how these settings do. You might see improvements because GPU freqencies are playing nicely

I'm surprised your sdram is so high without overclocking sdram. but if its working then no need to bump that up