Hi there,
maybe you do already and i haven't figured out it yet, since im fairly new to Speedrun.com, but wouldn't it make sense to categorize runs between PAL and NTSC decoding systems within the games section?
I know its not always the case, but living in europe and playing on original hardware, many games just run slower on PAL which makes it much harder to compete...
Splitting games by region site-wide is not a good idea. As you said, this is not always the case, so it wouldn't make any sense to force that onto games that this doesn't apply to at all. This sort of thing is handled per game. If there's a significant difference between two versions of a game then it's up to that game's community to decide whether to separate the boards or not. You'll be better off asking this question in regards to a particular game in the forums/Discord server for that game.
You can filter by regions tho' so you only see runs done on EU, US etc systems.
"I know its not always the case, but living in europe and playing on original hardware, many games just run slower on PAL which makes it much harder to compete..."
Which is why it's always been the standard to get your hands on the fastest version and run that. That's simply how speedrunning has always operated. There are more options now than ever before to do that.