I'll answer with a qualified "that depends".  In this case the size,activity of what you're hosting could impact performance.  It will impact the performance if only from the fact that more work will be placed on the same machine.   The biggest performance wedge comes when memory use is so high that the operating system is forced to swap to virtual memory forcing the workload to be "i/o bound" waiting on reading/writing memory pages to/from disk.

My experience has moved from having too few resources (many repositories, few machines) to one where resource limitations are much less a concern.    E.g. > 5 application servers + databases on same machine with limited RAM (32g) to LPAR with 80Gb ram, running 20+ repositories, separate database host.