That option was removed and new feature was created to help throttle scan and deployments. Tools > Options > Patch > Global Thread Pool.
Specifies the total number of threads that can be used during a patch scan or deployment, an asset scan or a power status scan. The value you specify will be multiplied by the number of logical CPUs on the console machine to determine the maximum number of threads that may be used during a scan instance. One thread will be used to scan one machine, so if you specify a maximum of 64 threads it means that 64 machines can be simultaneously scanned during one scan. Allowing many machines to be scanned at the same time requires more network resources. Reduce this number if you are scanning over a slow link.
Not an expert but just a quick look at these features seems to me that they are totally different.
The copy speed feature manages bandwidth for file copies, and the thread feature manages cpu threads for scans?
So is there a new version of the copy speed feature. If not, is there a plan to put one back in?
For customers that have bandwidth concerns, we suggest using agents with Distribution Servers. This will greatly reduce the amount bandwidth used for the scans and patch copying. You could also stay agentless for the scan and use Distribution Servers to same on bandwidth copying files to it.