No way to reduce time.
The reasons are 2. This code has so many nested headers that the time delay is inevitable. My opinion: "it's good to slice code in many modules to make more efficient library use, but the sparse definitions in hundreds of headers and the heavy macro coding is too much for me" (polite for bad coding? probably, even for embedded programming almost all compilers have a 'separate segment by function' to avoid wasting program memory, so this proliferation of headers is not necessary).
The second problem is the PellesC browser that surely isn't designed for such a mess (here would help a lot the MSVC precompiled headers...).
A suggestion to not wait, open a cmd window in the project folder and try:
> POVARS32
>pomake /F lvgl-9.0.0.ppj
If you're compiling for 64bits:
> POVARS64
>pomake /F lvgl-9.0.0.ppj