Allow the containers to use more than one core

[nicolaslara]

I haven't gone deep into the details here, but noticed that when running worspace-optimizer, it maxes out one of the CPUs while the rest are idle.

I tried passing --cpus 3.5 but it didn't make a difference.

[webmaster128]

It might be related to production builds for the Wasm target. Incremental builds don't work there too. Do you have a similar behaviour when doing a fresh compilation natively?