Inno Setup: Delay Before Progress Bar with Large Compressed Archives

[Ra7eN]

I’m teaching myself how to make installers with Inno Setup and learning by looking at example ISS files. My goal is to use compression tools like Precomp, LZ, and SREP to optimize the repacks. However, I’ve run into a bit of an issue and could use some clarification.

When I create installers with large, highly compressed archives (2-7GB), there’s often a delay of up to 3 minutes before the progress bar shows up during installation. At first, I thought it was freezing, but I waited it out and realized it was just taking time to decompress the files. The installation completes fine, but the delay makes it look like the installer is stuck, which isn’t great for user experience.

My main question is: does Inno Setup typically decompress archives into {tmp} (or another temp folder) before showing the progress bar? Or could this be related to how my ISS file is set up—maybe the order of commands or the way the installer processes compressed archives?

I’ve noticed other installers I’ve tested don’t show the progress bar immediately either when using heavy compression, but they seem a bit more responsive overall. I’m wondering if this kind of delay is just normal behavior for Precomp and SREP with Inno Setup, or if there’s something I might be missing in the scripting or compression settings.

If it helps, I can upload an example ISS file, but I figured this might be a general question about how Inno Setup handles things. If this is just how it works, I might stick with batch files for now, even though I prefer the visual appeal of a GUI. Any tips or insights would be awesome!

[dyren]

If you used precomp for compression, thats why.

[Ra7eN]

Originally Posted by dyren

If you used precomp for compression, thats why.

All right thanks for the quick reply. So I'm assuming also combined with s rep, makes it take even longer.
I'll just keep with the old fashioned bat files. I can get it to crunch down pretty small, but I'll take that over a fancy gui. Thanks again for the help

[dyren]

Originally Posted by Ra7eN

All right thanks for the quick reply. So I'm assuming also combined with s rep, makes it take even longer.
I'll just keep with the old fashioned bat files. I can get it to crunch down pretty small, but I'll take that over a fancy gui. Thanks again for the help

Nope, it only takes long because of precomp. I'd avoid it anyway, it doesn't do much in most cases.

[Masquerade]

It's not because of precomp, it's because of the lack of stdio processing for decompression. Whatever plugin you use to bridge FreeArc with InnoSetup will only record finalbytes written to disk. If you're using $$arcpackedfile$$.tmp / $$arcdatafile$$.tmp for any decompression commands, FreeArc has to write those files to disk, do decompression, THEN write the final files/bytes. This janky process is why you wait forever to see any progress.

You can save all this trouble by using stdin/stdout supported tools for decompression.