FLS Checker plugin

Thanks a lot for the app. Was it so difficult for steinberg to provide us at least with some little tool like this a while ago in order to at least no wonder about some weird disappearing plugins when re opening a project ??

Thanks for writing that article Lucas. In that article you are suggesting: “increasing the number of Windows processes to run plugins (why not offering 5 or 10 additional processes bringing each their additional FLS capacity, with either manual or automatic configuration per plugin - like a CPU can have 10 cores, a DAW could have 10 Windows processes to run plugins in and then the FLS issue would be totally gone)…”

I think that already exists if you are familiar with Vienna Ensemble Pro. Each new Vienna Ensemble Pro instance gives you a lot of new (free Slots for Plugins and Virtual Instruments). Like in your example, you could use Analog Lab (which occupies a lot) just in a new Vienna Ensemble Pro instances, without loosing available Slots (FLS) in the main daw…

Cheers, lokotus

PS: I thought Komplete Kontrol would also be beneficial to this issue, but it does not help for more slots like Vienna Ensemble Pro does.

JBridge can also be used to give you another 128 or slightly less slots.


It seems that adding to everything this is also system dependent

Running a project by double click, through Cubase shortcult or pinned to taskbar shortcut adds +2FLS
This way hub (“stripped” hub - without internet part) is completely bypassed which apparently needs 2 slots to run

Who would have thunk it. An option to disable stuff that you don’t use…

Regards :sunglasses:

You are right, it is. Different drivers will eat up a different amount of FLS. Hardware integration can also use up some more.
If you have a UR interface and additional MIDI / DAW controllers with hardware integration, FLS usage can increase a lot.
It also means that another way to increase the available slots is to turn off the controllers that are not needed… it could also help to connect a keyboard controller to the audio interface via MIDI, instead of plugging it via USB. During mixdown you don’t want to disable the DAW controller, but possibly don’t need the keyboard.

How many free fls slots on a empty project there is ,is kind of pointless.
The next plugin you load may take 47 or zero fls slots.
It is not like Cubase runs faster with more fls slots free.
It is interesting :slight_smile:

That’s for sure, but knowing where to get hold of a few more slots when the last 5 plugs you need to close the mix won’t fit, might come in handy :slight_smile:

It’s all relative, but with the latest Cubase release Steinberg streamlined their code and I got more slots, very welcome. Also, disabling the unneeded DLLs worked to give me even more as well as bypassing the Hub opening at the start.

I’m here in this thread because I have one project which has used up all the slots. I was stuck several months ago because I had a decent mix but I wanted to add an extra VSTi to try out a different sound, but I couldn’t because I didn’t have any slots left. I’m still a little bit stuck because I can’t use the instrument I wanted to, it takes too many slots even with the extras, but at least now with the FLS Checker I can manage my slots better.


Good to know. Does having more I/O through ASIO affect it? I’m running about 24 in and out.

jbridge was the answer for me. Mainly due to UAD plugins taking a lot of slots (I haven’t checked yet with FLS how many but they seemed to hit the limit far faster.)

Yes, using VEP instances connected to VEP processes on the same PC is another work-around for the FLS limitation and probably ReWire can be used for this as well (I did not do any testing on this). But having multiple DAW processes would offer a fully transparent solution and otherwise using jBridge is a much easier and cost-effective way when a few more slots are needed to complete a project.

When you configure jBridge to have each bridged VST starting a new Windows process, the number of VSTs you can add is not limited anymore by the FLS mechanism but only by the CPU capacity. You can see in the Windows task manager whether additional jBridged VSTs are added into one shared jBridge process or running each their own process.

Found this concise explanation of the FLS issue on Gearslutz ( 17th February 2018). I knew nothing about this until now. Thanks for the posts and the plug-in. I’ve not installed it yet but will post some info when I do.

Thanks, this plugin is very useful.
There are 3 approaches to fixing this issue:

  1. Plugin vendors use dynamic linking and include the appropriate redist in their installers.
  2. Cubase uses multiple processes to host plugins.
  3. MS provides a workaround.
  4. We all switch to Macs.

Even if every plugin vendor used dynamic linking and Cubase used no slots, we’re still stuck with a limit.
Theoretically 128, but most likely around 64 to 100.
I’m getting tired of throwing high end hardware at an OS issue, perhaps option 4 might be the best approach.

Slate Virtual Mix rack eats 36 slots.
can someone confirm same amount ?

I tried latest version ( and it showed me -2 slots for vst2 and vst3

Many thanks for the FLS Tool Takashi!

I’m finding just two slots for VMR vst2/3 also with the latest build.

This is kicking up some rather interesting results actually… The new Arturia preamps are rather hungry too with 8 for The 1973 and 6 for both the TridA and V76 respectively… Analogue Lab3 uses up a WHOPPING 45!!! think i feel a post coming on in the Arturia forum… :wink:

Ozone8 Maximiser uses 8 for vst2/3 which is also pretty hefty!

I think the Analog Lab plugins versions 2 and 3 instantiate every single plugin instrument in the collection immediately when started, whereas the version 1 instantiates the instruments as they are required by the presets (and they’re not released). That’s why they take up so many slots.

Arturia definitely need a (polite but firm) hauling over the coals for being so greedy :open_mouth: