Q: How many Portfolio items can I create?

A: As many as you like - please read our note below

Yes, you can create as many Portfolio items as you like.

However - please take into consideration that hundreds of Portfolio items in one Portfolio might slow down the visitors devices - especially when your visitors use mobile devices.

Our recommendation : If you really have several hundreds Portfolio items to display, split them into 2 or more Portfolios and make 2 different sections.

Example: if you have 100 Portfolio items with the topic 'cars' and another 100 Portfolio items with the topic 'motorbikes', then don't create 1 Portfolio with the main filters 'Cars' and 'Motorbikes'.
Instead, create one Portfolio for the cars and one for the Motorbikes. This allows you to create main filters for e.g. 'brand' , 'engine output' , etc. for both of them.
Take this in consideration: maybe someone who wants to informed about cars is not interested in motorbikes , and vice versa :-)