If you find you have a delay between pressing a key on midi keyboard and hearing the sound, here's how I solved the problem WITHOUT using jack
The problem is timer resolution.
The Ubuntu 'Karmic' (10.04) kernel currently is set to 250Hz timers, which is insufficient for MIDI. Here's how to correct this:
sudo su -c 'echo 1024 >> /sys/class/rtc/rtc0/max_user_freq'
Reboot your machine, and you should find that the sound and midi event now are in sync.
SOURCE: https://help.ubuntu.com/community/UbuntuStudio/DapperPreparation (Under the heading Timer Resolution)
