The Cpu usage is low when starting about 10-20%. When sounds are played the cpu usage gets higher and higher and reaches about 70% and then sounds are very distorted. If sounds are disabled, CPU usage stays in 10-20% range. Sounds distortion happens in Lumia 1020 (WP 8.1) . In the emulator I have had no sounds problems. The culprit might be SharpDx sounds dll.