This depends on your computer. With a Pentium 4, 2.8 Ghz, and 1 gigabyte of RAM, users have reported running up to eighty instruments at once as a VST plug-in Users with a slower Pentium 2.0 reported loading over 50 instruments. Users with slower processors - like a 1 Ghz Mac report about 20 instruments. Your experience may vary depending on your settings, programs, configuration and other factors. The Kontakt audio engine is designed to make use of the processing power of your computer's CPU. The powerful and complex algorithms of the Kontakt Player work best on modern CPUs.