Improve startup by disabling CPU-hungry themes

Description

The 'Substance' theme pack includes three themes that use a Noise generator (I'm assuming it's a random generator) that gobbles up resources. For me, each theme adds 2 seconds to the startup time of Spark - even when the themes are not used.

We should prevent these themes from adding so much overhead.

Environment

None
Fixed

Priority

Minor

Assignee

Guus der Kinderen

Reporter

Guus der Kinderen