Rony, I'll cover the sp_trace* procs in detail in the next Stairway level, How to Create a SQL Trace Using T-SQL.
With client-side traces, a SQL Trace rowset provider runs on the server to handle returning trace results to the client application. If the client doesn't consume trace data as fast as it is generated, the trace buffers fill on the server and server threads sending event data will wait for free buffers. Consequently, a slow trace consumer can slow down queries and overall server performance. The rowset provider waits up to 20 seconds before dropping trace events.