FLS Checker plugin

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:


Yes GargoyleStudio it would seem you’re correct re AL & AL3…
Posted on the Arturia forum and got a fairly speedy and gracious reply from Ben… https://forum.arturia.com/index.php?topic=92788.new;topicseen#new if anyone else wants to contribute there too.

Some of the results i’ve been finding are quite surprising… Spectrasonics Trilian only uses ONE FLS slot which was unexpected as it’s a bit of a beast!
BFD3 only uses 2 and again it’s a bit of a beast…

Thanks for that @matjones, very interesting!! I’ll be hoping that they can do something to help. I couldn’t seem to log into the forum, is it different to the Arturia account login?? It doesn’t seem obvious, there’s no info…


FWIW, Ben (I think he leads the beta test group) is the guy who handles Arturias bugs. I had many problems with Arturia “support” until he got involved, and within weeks they fixed a glaring sustain bug with the Prophet V. He is very active, hands on, and will work with you. Just communicate and don’t drop the ball…

Question, so each of my hardware synths plugged in via usb would be using extra slots?

Not necessarily, but if they have integration (usually a dll in the Components or Shared Components folder of Cubase), yes they will.
The UR interfaces also use some slots.