Concurrency level and time cost converting psd to pdf

I am converting psd to pdf. I got 3 questions to ask:

  1. it took me 3 mins to convert a 30MB psd into pdf(ubuntu 4c8g), how to accelerate? Normally how long would cost to convert 10MB\20MB\50MB\100MB psd files to pdf?
  2. how many java threads can work properly at same time(ubuntu 4c8g)
  3. i got warn messages as below, but in font directory, the font exist.

Trying to install font family SimSun at /usr/share/fonts/truetype/simsun/simsun.ttc to private collection
Font family SimSun with style Regular is not available: please, try to reinstall this font
Trying to install font family NSimSun at /usr/share/fonts/truetype/simsun/simsun.ttc to private collection
Font family NSimSun with style Regular is not available: please, try to reinstall this font
Font cache was not available for : Montserrat-Regular
Font cache was not available for : Montserrat-Regular
Font cache was not available for : Montserrat-Regular
Font cache was not available for : Montserrat-Regular
Font cache was not available for : Montserrat-Regular

@guguzzz could you please provide source file and code that you used for the conversion.
Quick answer: The size of file is not the main reason that can affect the performance.
You can try use ReadOnlyMode PsdLoadOptions - Aspose.PSD for Java - API Reference

Thank you for your reply, the main part of my code is as below,

    PsdLoadOptions loadOptions = new PsdLoadOptions();
    loadOptions.setReadOnlyMode(true);
    Image image = Image.load(srcPath,loadOptions);
    PdfOptions options = new PdfOptions();
    image.save(destName, options);

I used ReadOnlyMode, the time cost reduced to 10 seconds, and no fonts error any more, Nice! My question remain only one: What is the recommended number of threads for a 4c8g machine?

@guguzzz not every PSD processing operation can be parallelized. I think that in a typical case, one thread per one file processed at the same time is enough