XnView Software

I did a test with the latest IrfanView 4.62 (webp library 1.32) and XnviewMP 1.5.5 (webp 1.30).
For conversion I used a folder with around 300 png files (1920x1080 pixel - loseless compression) and converted them directory to webp loseless.

IrfanView took around 6 minutes.
Xnviewmp need around 26 or more minutes.

Both compressed the files to the same size, but sometimes XnvIewmp compressed them up to 2% better.

Why is XnViewMP so slow?

I do not have any settings in the conversion list.
Does the new webp 1.32 library have a performance optimization? I did not read anything about it.

i've tried, and have same speed. Which options for WebP?

I did the test again with 3 png files. In the past Xnviewmp and irfanview did the conversion job in the same time.

XnviewMP 1.5.5 needs 1 minute and 32 seconds! (Around 30 seconds per file)
Irfanview 4.62 (with latest webp 1.3.2) did the conversion in 11 seconds! (4 seconds per file)

If you convert around 100 files, the time is much bigger.

Here you can see my irfanview settings:

xnviewmp settings:

really strange, i have 5sec per file on both. Please send me a png sample file?

Here is a link for a sample png file:

https://www.dropbox.com/scl/fi/2jsccqbc ... s0ncx&dl=0

Thanks to your detailed description I can reproduce the problem.
It's related to method > 4

Good news! Thank you!

Hello,

Just for information, you can significantly improve performance during mass conversions by activating the "use multiple CPU cores" option.

This problem is supposed to be fixed in XnView MP 1.6.0. Please check and confirm the bug fix here.