Retropie performance extremely slow on 4k TV

Rubicai

Hi everyone I hope I can get an answer in here. I've got my first raspberry pi today, and while setting it up everything went really well. I've installed raspbian, retropie and redream (it's a raspberry pi 4 btw) and the performance was great, from cps2 to psx and dreamcast. I did that on a smaller TV, like 20" or so. After everything was set up, I moved the raspberry pi to the living room where I have my 50" 4k Sony Bravia (I add the model because I don't know if that's crucial or not). To my surprise, it's a total mess. I can live with the black borders displayed around the screen, but the texts are really small, I'd say even unreadable, and most importantly, retropie is very slow. It takes a lot of time to load the main screen and it's completely unplayable. On the other hand, redream works well, but it's set to 640x480, leaving me with a small image in the center of the screen. So well, my questions are:
1: is there any solution to the small text? Can it be resized so that it matches with the screen?
2: is there a way to get redream to display a bigger image without losing speed?
3: how can I fix retropie? Can it still be displayed to fit the entire screen and be playable?

Pd: sorry if I misspelled something, English is not my first language.

Rubicai

@Rubicai Okay I've finally fixed it. If someone is going through the same problem contact me and I'll tell you what worked for me.

quicksilver

@Rubicai there is no private message function on the forum. Any chance you could post the solution here in case others have the same issue?

Darksavior

The answer is to set the resolution to 1080p via raspi-config or manually through your config.txt. You're welcome.
For redream, 640x480 or 720x480 is the optimal resolution and you set that inside the emulator.

Rubicai

@quicksilver oh okay sorry, I was thinking maybe via email too but I'll post it

Rubicai

@Darksavior I had the raspberry connected in the HDMI 0 port, I changed it to the other and it's not the highest resolution but I don't really need it. I just thought both ports were the same that's why I didn't bother changing it until last minute, but thanks for replying!

squanto

This is how I fixed laggy N64 performance on my 4K tv:

hit F4
cd /boot
sudo vi config.txt

in config.txt, add the following to force 1080p:

hdmi_group=2
hdmi_mode=82

[hdmi:0]
hdmi_max_pixel_freq=200000000

[hdmi:1]
hdmi_max_pixel_freq=200000000