Just swapped to a 4K monitor and now my old graphics card can’t handle simple video playback smoothly

I recently upgraded my setup to include a 27-inch 4K monitor because I wanted sharper text and more screen real estate for coding and casual gaming. My problem is that my 5-year-old mid-range GPU, which handled 1080p without a hitch, now struggles to play even 4K YouTube videos without stuttering or lag. I’ve tried updating drivers, lowering video quality settings, and closing background apps, but the playback is still choppy. I prefer not to upgrade my entire PC just yet, as I’m on a budget and want to squeeze more life out of what I have. Does anyone know if there are tweaks or software solutions that could help smooth out 4K video playback on older graphics cards? Or is the only real fix to upgrade the GPU? Also, could using a different media player rather than a browser help?