opencv slow on ubuntu

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hi, i have written an application to detect roads. the input to my program comes from an IP camera. i use opencv 2.4.0, eclipse IDE and ubuntu 11.10. the program works but the frame rate is really slow (i get one frame every 4 seconds). i have tested the same code on windows using opencv 2.1.0 and visual c 2008. the code on windows works perfectly fine (almost real-time). but as i said the same code on ubuntu has terrible performance. the road detection is based on Hough transform. one last point i have to mention is that if i comment all the processing done on the input, the frame rate will become real-time on ubuntu but if i do the processing needed to detect roads the frame-rate will drop very low.