Low FPS even though I installed dgVoodo 2. FPS falls even more during explosions.

If you're experiencing low FPS, this fixed it for me.

[url=https://pcgamingwiki.com/wiki/Blood_II:_The_Chosen#Run_Blood_II_on_modern_systems]https://pcgamingwiki.com/wiki/Blood_II:_The_Chosen#Run_Blood_II_on_modern_systems[/url]
Download and use the ddraw.ini from here. It's at the very bottom of the section "Run Blood II on modern systems".

I use this in combination with the dgVoodoo wrapper.
http://dege.freeweb.hu/dgVoodoo2/dgVoodoo2.html
The widescreen FOV fix.
http://www.wsgf.org/forums/viewtopic.php?f=64&t=27095
Install the ddraw.ini after dgVoodoo2, overwriting existing files if necessary.

I also use the music fix.
https://community.pcgamingwiki.com/files/file/1231-shogo-prefixed-am18dll-and-dgvoodoo2-setting-suggestions/

The game's always had issues with FPS dropping during explosions. Even with my newer Win10 rig with 8gigs of VRAM and 64gigs of RAM and an i9 CPU, I get lower frame rates when the explosions happen--noticeably with the Bullgut.

Why that is I couldn't tell you, but someone else posted the same observation on another thread.

Part of it may be that the explosions use the full spectrum of true color, and with all the action of particles and smoke trails arcing everywhere, it just may be too much for video cards of any era to render.