I made a video to demonstrate the issue.



Vegas Pro 14 - Build 270

Vegas Movie Studio 15 - Build 116

I can not see much difference in rendering time on my machine. I have tested with VP14 VP15 and VMS15.

But:
There is a issue with memory usage in all tested versions. When a folder with many files (eg. Image Sequence) is opened in Explorer, memory usage skyrocket. You can avoid this by disabling the thumbnails in Vegas Explorer. Check memory usage during opening, editing and rendering. Less free memory leads to slower rendering.
Maybe that is the raison.

I was wondering if anyone has experienced very slow rendering time in Movie Studio 15 with a PNG Image Sequence.

I confirm this behaviour in VMS 15 Pl. on laptop and Windows 10 latest updates.
Tested with Pro 13, Pro 15, Pro 15 and VMS Pl 15, all latest builds.
All rendertimes are different for 500 PNG stills in a sequence to render to Sony AVC FHD internet 30fps.
- VPro 13 takes 21 sec.
- Vpro 14......... 14 sec
- Vpro 15......... 15 sec
- but VMS Pl 15.............85 sec

Look for the results my screenvideo

But this is only happening when I render to 30p out of a 50p project with a 50p sequence file, when I render to 30p out of a 30p project and a 30p sequence file the results are equal.
My video will follow.
Look

I tested again, Win7:

500 JPGs stills in a sequence FHD Sony AVC/MVC FHD 30p
VP14 39sec
VP15 81sec, with repeated rendering each 38s
VMS15 76sec repeated redering each 38s
Did you render a second time and see if the rendering time is shortened?

That's a very strange behavior.

In the first video VPro Sony AVC 30p are compared with VMS 15 Image Sequence PNG.
Sequence, project and render settings should be the same to the test.

Didn't I say that here?

But this is only happening when I render to 30p out of a 50p project with a 50p sequence file, when I render to 30p out of a 30p project and a 30p sequence file the results are equal.

but this means that for the Pro versions it makes no difference in rendertime ( and result?) to render to every format and that alone for VMS 15 it makes a big difference.
And therefore maybe you have to use the right files in the right project for rendering to that same format? I never experienced that behaviour before VMS 15.
When I used the procedure of Video 1 also for VMS Pl 14 the rendertime took 43 seconds, also longer than the Pro versions but the rendertime in VMS Pl 15 was almost twice that time.

I'm glad to see I'm not the only one, but if I'm understanding correct, it seems like we might have slightly different results. In my video above, it is a 29.97 PNG Image Sequence, in a 29.97 Project, Exporting under the "Internet 1920x1080-30p" settings, which both are default 29.97 (in Vegas and Movie Studio). You can confirm these settings in the video I posted - yet for some reason, Movie Studio is so much slower. :(

....., but if I'm understanding correct, it seems like we might have slightly different results.

In my 2nd video I followed exactly the steps and settings you did and there was no difference in rendertimes for me.
What this is causing the different behaviour for you I have no idea, because I don't know your hardware and settings, builds, etc for both versions of Vegas.

VP15 81sec, with repeated rendering each 38s
VMS15 76sec repeated rendering each 38s

When I render the first time, it takes much longer. Times are shorter for a 2nd renderer. As expected, VP15 and VMS15 deliver the same results. The then shorter times on the 2nd render are comparable to VP14. I tested it with a sequence of 500jps, where sequence, project settings and render settings are the same (29.97fps). Thumbnails were deactivated and the explorer window was closed.

I think that this is a bug. How Vegas scans the current folder in the background is very suspicious.
My assumption: This scanning is completed during repeated rendering. That's why it's faster. In VP14, this scanning does not take place.

I will examine this assumption again.

If you want to know *exactly* what the software does on the file system, download Process Monitor (https://docs.microsoft.com/en-us/sysinternals/downloads/procmon), set up a filter on the MS process and you'll have perfect info of what it's trying to do when.

Thanks, Yes, I always do that.
My guess has been confirmed, at least on my computer. The first render accesses files in the folder that are currently not used in the project.
Vegas 15 is concerned with files that are currently not needed. That costs time. When repeatedly rendering, only needed files will be accessed as with VP14.

I reported the error to Magix [Ticket#2018042717005427]

And what has the OP have to do to overcome his problem?

Thanks to everyone's involvement in this. I'll admit that due to time constraints, I just flipped back to Vegas Pro 14 when I saw multiple people were having issues (I also saw that there were for more experience people working on diagnosing the issue). I'd really like to be able to use some of the features in MS15 - I was curious if anyone did know of a work around for this issue?

Thanks to everyone for their help.