The answer is, depending on your needs, but you are not here to hear that now are you, so I did a little experiment, tailored specifically for a certain need that does not apply accross the board, but combined with other experiments online, this might give you an idea
The experiment is annotating an image with image magic plugin for PHP
Both running buster (Debian/Raspbian 10), both on PHP7.3 and everything fresh installed
the PC has 8GB of DDR3 Ram, and the PI 1GB of LPDDR2-900 SDRAM
The PC has a 12 year old “Intel(R) Core(TM)2 Quad CPU Q9450 @ 2.66GHz”
The PC was around 7 fold faster than the raspberry PI 3 (the mean of a trial of 20 runs, with all the files cached in ram by the linux kernel)
The trial was done with a discrete VGA card (AMD RADEON) and with the chipset’s own graphics card, results were identical (The VGA card did not have it’s drivers installed, so we don’t know if it might have an effect or not)
I am now moving into even older PCs to compare performance, and will report the results here again to see what the limiting factors might be