>Actually my company sometime the sql server run out of resource and become slowly . Then my head will said those query with Multiple ECIDs must kill the process and it must be the reason of make the sql sever out of resource and become slowly. By your answer is it mean that Multiple ECIDs is usually happen. for those query with Multiple ECIDs dose not mean those query not optimize. IF a query with single ECID if not optimize also will make the sql server run out of resource and become slowly. Am I correct ?

Yes unoptimized queries can severely affect SQL Server performance.