Can multiple cores be used for brute force optimizations? Without using walk forward?

Yes, but only with Walk Forward.

Is it planned to include this functionality in a future version? It would greatly speed up the optimization

Why would you want to optimize without Walk Forward?

If I have 32 cores and if i use 5 walkforward periods, the strategy only uses 5 cores. It would be nice to be able to use all the cores. Also, when testing new ideas before applying the walkforward, I run several optimizations without walkforward. It would be great to take full advantage of the computer's power

Use NumCores to set the number of cores.

https://zorro-project.com/manual/en/numcores.htm

Testing ideas by in-sample optimizing is not a good idea. First, it is slower, second, the results are misleading.

You can use multiple cores only for tasks that can be parallelized, such as the cycles of a Walk Forward optimization. A single cycle with a single asset cannot be further parallelized.