My Windows systems all open a 2500 book Library in well less than a minute (But not anywhere as snappy as the claims I see around here
)
I have 1G or more RAM in every one.
Calibre is NOT graphics card intensive. If it handles your Screen resolution and color depth, you are good.
Tame your Antivirus. It does not need to actively check (real time scan) your Library Folders files . Those books were checked in the folders that they were in when you imported them.
My Linux systems (same HW) run faster.