wcf service and Entity framework.....

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C#

hi everyone,
I have problem with wcf service and entity framework....

my problem:

wcf service:
it is suitable or not if i create a project using wcf service to store all my function for working with db? if not,can you tell me about the problem?

entity framework:
I test query with sql server.The result is really slow down.why entity framework is really slow like this so when should I use entity framework?

thank in advanced.....