Using tiles many times without lag?

There are many tiles for things such as grass, dirt and so on, but in order to cover a larger map you either have to strech them out so they look ugly, or copy paste them a million times. Is there a way to set a tile as the "background" where it would just copy itself over and over again? Or is there maybe something else i can do so i don't have a ridicules amount of pictures to load on every map?

If you want to do something like that you have to make it by yourself. Get a graphical software like GIMP, it's free. Then just compose the image the way you want it to be and export it as a single picture. It's some extra work, sure, but you can get stuff exactly as you want them to be. Roll20 does not offer tiling backgrounds, as far as I know.

Michael K, I would suggest you consider making your own using free textures sites, there are some that use Creative Commons style licenses.

There are some API solutions that might be modified to work for tiling but two things stand in the way. One: you or the games creator would have to be a pro subscriber to use the API script. Two: you or the game creator would have to, possibly, modify the script to function or politely ask one of the script gurus to do it for you.

I personally use MapTool to create my maps and export it as a single image. This lets you use lots of different tiles and combine them into one big map.