Modern Sound Cards do not have a Hardware MIDI Synthesizer on board any more.
Therefore, for lack of a Hardware Synth, by default the "MS GS Wavetable SW 
Synth" or "MIDI Mapper" are used, which are OK for MIDI file playback purposes
but have the known Latency issue when using external Keyboards. 

Technology is moving away from MIDI, as Digital Audio and other formats such
as MP3 etc. are prevailing on the market.  Current Sound Cards (unless you go
for Semi-Pro and Pro level at a few hundred $$$) are not complimentary for 
MIDI and issues such as Latency, poor quality etc. are present due to the 
Software Synth.

The good news is that external MIDI Modules have become affordable, providing
better quality sound and overcoming any Latency issues.
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