Ah, after digging a bit through the buildconfiguration apparently in Unreal 5.6 the UBAExecutor is now enabled by default, where it was disabled by default in 5.5.
After manually disabling it I’m getting back to my old compilation speed of ~90 seconds instead of 10min.
For anyone encountering the same problem, edit your BuildConfiguration.xml to this:
<?xml version="1.0" encoding="utf-8" ?>
<Configuration xmlns="https://www.unrealengine.com/BuildConfiguration">
<BuildConfiguration>
<bAllowUBAExecutor>false</bAllowUBAExecutor>
</BuildConfiguration>
</Configuration>
Bit strange why this change in default behavior wasn’t in the patch notes. 