How big can I make my maps?

Hi All, I plan to make a ruined city for my players to explore. So my question is how big can I make the map squares X squares? I plan to make the map using art in roll20 not upload a big jpg file. I know that there technically should be no limit but I read somewhere here on the forums, that some people have had problems with maps bigger than 40x40. That topic is 4 years old so maybe it has changed in the meantime. Do any of you have expirience with larger maps?  

In my experience the amount of items on the map has a bigger impact then the size but the only real issue I've experienced are longer loading times. The largest map I've ever done myself was 126x86 un. and it worked just fine. Dynamic lightning, dungeon dressing, clutter and all.

um. I know a lot of players have issues with maps that are 1000x1000, as threads pop up in the bug forum from time to time about it.

Thank you for the reply. I am planning to make 100x100 sections, so that should be fine then. I was concerned about FOW and dynamic lighting not working properly and revealing the map to the players prematurely.

It depends on the the computers used by the players and the amount of graphic that exists in a single map. Here are some examples from my experience: 1. 100x100 map with a single image will run smooth even on toasters. 2. 100x100 map whose map images are single elements split into several small units will start causing major lag on toasters but will run fine on moderate PCs. (For example, when you use map generators with API such as DungeonConnect) 3. 100x100 maps made with single elements and with dynamic lighting on top of it will completely annihilate toasters and cause major issues on moderate PCs. PCs that cannot handle dynamic lighting will result in their browsers malfunctioning and getting rid of dynamic lighting altogether for them. Make sure you create dummy pages and test each individual players on them.

OK I think one player has an older moderate PC. I probably should go with 50x50 maps just to be sure.