webp is have very long loading time(decompression) in game. On html it is super slow.
In one my big game. We use webp only for backgrounds. Because when we use it for everything, loading was slower then without webp. 
We have 5 different background, 1 for every zone.
So when game start we load in memory only one.
Not sure about loading time of BASIC:)
Is someone make tests?
Some old tests.