If we installed about 40 components, 60 modules and their related plugins in the master site, and used them across 40- 50 sites, what kind of performance should we expect? Would we need to run the master/slave sites in a customized hosting environment? Please help us to know what to expect. What would you recommend?

Thanks!

If you have understood the concept of JMS, you share the same Joomla PHP code and use Symbolic Link to share the files and folders.
So that, when a domain is resolved by apache, it gives starts the application present in the "document root".
As the document root contains all the files and folders with potential links, the overhead of JMS can be 0 Sec as all the job is already done by apache.
If you uninstall JMS, your slave site can continue working like a slave site because the stuff is done in the architecture of the files and folders on the disk and also in the MySQL DB.

When JMS is present, there is a little overhead that is added to read the slave site definition but this overhead start to become significant when you have more than 1,000 websites.

So in your case, you can consider that 1 website with 1,000 hits is moreless equal to 50 websites with 20 hits (50*20=1000)

So the most important is the number of hits expected.