Wifi extender for 5 hz (2-3/4 bars) OR switch to 2.4?

In my bedroom, I get between 2 and 3 bars of wifi coverage out of 4. I do have a WiFi extender, but I'm not sure if switching to 2.4 off the router directly would produce better speeds than 5 from the extender. Or does 5 directly from the router, even at lower strength, still produce the fastest speed?

I could try it myself, and likely will, but i wanted to see if one option is expected to be obscenely superior to the other.