As lovely as it looked, I've had to strip away tons of the lines drawn in the tunnel.

-=-=-



It's not as pretty, but it does as least now flow smoothly.
Today I'll be throwing in some sprites and hoping it can keep up the framerate.
The worry is that switching between solid lines, to sprites and back again (in order to keep the z-order stuff working) might end up slowing things down again.
Not really sure how well browsers can cope with that.
Some browsers will struggle if you switch between Text and Sprites, but hopefully Primitive and Sprites won't be so disasterous.
*shrugs*