Reduce DataBase Size

Dear friends,

iam usin p6 v8.1, sql

the data base is very slowww. the MDF file size is 3.40 GB and LDF file size is 5kb . i tried to delete some projects to decrese the size of MDF file to make it more faster, but the surprise that after seleting 4 projects the size is increased to 3.5 GB. I made shrink for the data base but this dosn't help. there is one file on these forums oncluding some queries like:

update statistics project with fullscan ,all
update statistics task with fullscan ,all

&

exec sp_updatestats

But also this doesn't help. and the problem is the data base became more slower after deleting these projects.

Please i need quick help

Thanks