Yeah, that's what I've been having to do on a lot of things lately. I told them what would happen when they first started pushing it. Looked at the person next to me to say, with all the things Win98 on a PII did, the modern era chokes a Core Duo 2 trying to look at a document in a browser. Unreal...
JS is also sandboxed, which seems to be a particular problem for traditional readers. I’d trust PDF.JS to get faster more than I trust PDFium to not have security issues.