You can hotlink PLP files but I wouldn't as you rightly say it's to slow. Instead Publish modules of just the data you need in the other PLP and Hotlink to those.
For example we have PLP that contains the main elements that make up the Project. We then have other PLP files that connect to modules Published from the Propject PLP to create specific drawings such Escape Signage, Stair construction, Floor finishes etc.
This avoids having a huge Project file thereby speeding up sending and receiving as only data that is used more than once is in the Project PLP whereas the other PLPs contain data that will only be used once and again they are as small as possible to again speed up sending and recieving and saving.
AC versions 3.41 to 25 (UKI Full 5005).
Using AC25 5005 UKI FULL
Mac OSX 10.15.7 (19G2021) Mac Pro-2013 32gbRam AMD FirePro D500 3072 MB graphics