Hi,
for a while build times have been much improved.
I just updated to the latest VM and also updated to the latest ESP32 core.
Sadly build times are back to sufficient time to make a coffee..

First build (after a Clean build) 191.54 seconds
Rebuild (having changed absolutely nothing) 195.43 seconds.
I have attached the build output.

In build.txt I have:

Build (using the build icon)

Yes it's doing full lib discovery too but with your board.txt it should not if no changes to the .ino

It looks like a rebuild not a 2nd build. The prototypes are also not found, it should at least discover setup and loop.

You do have two errors shown, not sure if that would cause it.

Ignoring source code that is included in the project but can not be located: S:\Arduino\Avionics\ImuCan\cct.cpp
Ignoring source code that is included in the project but can not be located: S:\Arduino\Avionics\ImuCan\cct.h

If you look at the solution explorer you should see that there are two exclamation marks or errors showing for two missing files. Right click them and remove/exclude.

If that does not solve then please zip and email your .ino code to us.

The project you send wasn't recognised as an arduino project. we will look into why that is.

As a test, remove the vcxproj files from the sketch dir and then use file>open>arduino project to reopen the ImuCan.ino

btw: I suspect this should also be in the ImuIncludes.h intsead of .ino. The .h has pragma once. ...

extern void setupImu();

The vcxproj was okay, I called the folder Imu instead of ImuCan

Where does device.h come from which is referenced in you bmeSensor.h and please send the canCodes.h which might be the issue.

I don´t know if it´s relevant but on several of the include files, if I right click and select Go to document I get a message 
"File ´xxx´ not found in current source file´s directory or in build system path"

@Acurio 

We noticed your libraries are always being recompiled. They have seperate cache options in the vmicro F4 project properties. Either the lib caching has been switched off or something is causing the library sources to be updated. That would also cause the deep search to klick off again.

Do you get the same problem in a new project?

We also noticed you have an #include to a fixed path s:\. It's better to use a shared code project for that include. Not sure if that is related but it's definately out of the oridinary

It is set to False

I have emailed various build outputs.
Hope they are helpful.

I tried that and the long compiles stopped.
So bit by bit I transferred my whole project to a new project, checking at each stage the compile times.
I now have the whole project copied over and compile times are now short.
So it´s a mystery what happened to the project.

One odd thing I noted when building, some project files are always recompiled even though they haven´t changed. I tried to work out why but another mystery. I thought it was something to do with the length of the file name but it doesn´t seem to be consistent.

Adding a new file with a different name (.h and .cpp) to the project and copying the code from the old file to the new file stops it recompiling every time.