Long tiled/tilemaps level - how far can you go on mobile when you don't have any other effects/animations?

[kriket]

I am in the process of building a mobile platformer using tilemaps. At this concept stage, where I am designing the art, how long can my tiled level possibly be before it starts running slow on mobile. I won't have anything much happening in the level, other than a character (animated via spritesheet), moving around the level. 

 

No other effects, or characters whatsoever. 

 

Will be made with phaser of course.

 

 

 

5000px by 2000px?

10,000px by 5000px?

[kriket]

Only asking cos I read somewhere that its best to keep it below 4096px if you're targetting mobile. So 256x256 tiles of 16px-by-16px each.