I tried to implement this to test this small speed acceleration on a RPi5 8G.
https://forums.raspberrypi.com/viewtopic.php?t=378276
But unfortunately I can’t get it to work 
Anybody with more RPi knowledge can explain? Or tell whether it could/couldn’t work?
At least a 10% speed increase could be the outcome.
Regards
PS: Just saw that this is a similar thread like Raspberry Pi 5 4GB is faster than the 8GB version - #3 by wanthalf
More soup for you tonight…
While grinding my rock soup, in my apologies, I have to note, that this question was not answered within the older thread, which tended to get lost into built-in wifi and BT discussions.
Regards
No need, it’s always rather enjoyable to watch people thought processes working in front of you.
I remember the discussion and my existing Pi5 (My desktop machine, it’s not made it into a zynthian yet). is probably due to be replaced by a Pi500 but I’m also thinking of upgrading the cajon to a Pi5 so I will probably go for a 4G.
I don’t know if the differences are baked in or might disappear in some future software update.
This sort of thing has the ability to pass into legend if not carefully recorded and re-examined.
We might well spill a little of your soup in recognition . . .
Important: The following only applies to RPi5 with 8GB RAM!
The SDRAM_BANKLOW=1 boot option is default in newer EEPROM versions since rpi-eeprom v2025.01.22-2712 and it works very well, gives a nice boost in performace.
It may be set manually in eeprom-config to be sure.
Please do not try hacks with older bootloaders.
PS: See the version of the bootloader eeprom via terminal:
vcgencmd bootloader_version
Update to the latest eeprom via terminal:
raspi-config
Then select update this tool or similar (wording changes now and then) and let run.
Restart raspi-config, look for something like bootloader version (can be inside advanced) then latest-something. Ok. Let reboot. Recheck.
In Terminal to edit boot eeprom config:
sudo -E rpi-eeprom-config --edit
A good and fast one is:
[all]
SDRAM_BANKLOW=1
HDMI_DELAY=0
BOOT_UART=0
NET_INSTALL_AT_POWER_ON=0
NET_INSTALL_ENABLED=0
USB_MSD_DISCOVER_TIMEOUT=1000
BOOT_ORDER=0xf164
POWER_OFF_ON_HALT=1
CTRL-s to save, CTRL-x to exit. This gives the option to boot a USB stick to make repairs or to play something else, without noticable delay when booting other memory devices, then boots NVMe and then µSD, all without big delay. Overall it is the fastest boot config possible nowadays. If it makes problems with NVMe or super-slow USB drive, just leave it blank and set the boot order inside raspi-config.
For Pi4, the parameter should be
SDRAM_BANKLOW=3