HACK: fix draw on firefox

Signed-off-by: Niv Sardi <xaiki@evilgiggle.com>
only calculate bounds on new data

Signed-off-by: Niv Sardi <xaiki@evilgiggle.com>
profiling shows that diff is slow, this is a caching attempt,

I think we can do better with a tick

Signed-off-by: Niv Sardi <xaiki@evilgiggle.com>