too slow to read pdfs with many pages?

[alanine]

I've a 267-page pdf file, pure text, 1.8M in size, which I don't consider a big size. But ipdf seems to take forever (around 12 seconds) to load a new page freshly. I wonder if anyone has experienced similar situation.

It also seems to do some caching for the next pages in the background, so speed is non-issue if I go to the next page after spending time to read current one. But unfortunately, my PDF is fully of cross-references, which allows non-linear jump.

A 500MHz CPU this slow sounds absurd. I mean, I use a PIII 500MHz 192M RAM laptop daily, which is never this bad. Also, pdf is a format designed for random access (if not perfect), so jumping pages shouldn't be that much of an issue. I wonder if anything could be done to ipdf to make this aspect faster.

[Adam B.]

It sounds like it's a complicated PDF. I don't typically have a problem with PDF's of that size. Would you be able to post it so that we can determine what the issue is. That's really not typical...

[alanine]

Originally Posted by Adam B.

It sounds like it's a complicated PDF. I don't typically have a problem with PDF's of that size. Would you be able to post it so that we can determine what the issue is. That's really not typical...

Indeed it's a PDF with embeded Chinese Type1 font created from Latex. Most likely you don't read Chinese, but I'm attaching it here anyway.

I just tried the same file on my PIII 500MHz laptop. Acrobat Reader 5 loads every page almost instantly, but xpdf takes like 5 to 9 seconds.

Then again, it takes forever to load Adobe's PDF reference document (over 30M in size) on iLiad, but once it's loaded, access to each page is anywhere between 1-3 seconds. This leads me to believe it's probably got something to do with the embed fonts that I use. xpdf/ipdf apparently don't handle them very well, but this is also something with room to improve as Adobe is already doing better.

[HarryT]

Embedded fonts will dramatically slow down the page rendering speed. That's almost certainly your problem.

[alanine]

Originally Posted by HarryT

Embedded fonts will dramatically slow down the page rendering speed. That's almost certainly your problem.

You are right, but only partially right. I spent a whole day digging this issue, and finally found a solution.

xpdf/ipdf don't have a problem rendering embeded fonts, but dealing pdf files with big number of embeded font sets. The file I provided above embeds many sets (90+) of Chinese Type1 font, though each is small in size. xpdf/ipdf are really slow at handling this, while Acrobat Reader and even GS/GV can do the job much better.

This becomes apparent to me when I notice some pdf files created by others that also embed Chinese fonts but xpdf/ipdf won't choke on them. The difference is that they embed Truetype fonts, which unlike Type1 with only 265 max glyphs, may contain thousands in one set. Thus it suffices to embed only 1 or 2 sets of bigger Truetype font in the pdf, v.s., the 90+ smaller Type1 font sets.

The solution to my problem is to create pdf using latex + dvipdfmx, which is able to embed Truetype without rasterizing them (just lilke Type1) in to the final PDFs. I'm attaching the result here. The file size is also smaller than the previous one but not by much, and the speed is blazing fast.

Of course the ultimate solution is to fix xpdf/ipf, but for the moment this little PDF creation trick plays well. I'll document this process in thorough detail on the Content forum, just to help other CJK users.