Delete equipment and SQL

Hi Le Duc Tho , Could you please let us know the system configuration like the OS, RAM etc. And for deleting the symbols please find this article and let us know whether it helped you or not. communities.bentley.com/.../7531.delete-remnants-of-a-symbol

This is configuration of mine....

It looks fine. Are you using a network based SQL database or a Local database ? If you are using the network database please try using the local database and check the speed once. And also are you facing this slowness issue with a particular project or for all the projects?

Thank you sir.
I am using a local database... when i start new project, it only has some equipment then run fast... but when full 220kV substation then i open project run very slow (about 10 minuted)... and insert very slow... i can't finish project because it load very slow...
please help me...Thank you so much.

Before trying anything else, I would first backup the project using Project Manager.

The file just might be so large, containing so many elements, that it is difficult to open and handle. In case it contains cells for symbols no longer in the DGN file, you could try the following:

1. Select File > Compress > Options
2. Set the Delete Unused Named Shared Cells and Delete Unused Anonymous Shared Cells check boxes.
3. Click Compress

Another recommendation is to use symbols with geometry that is as simple as possible. If every nut and bolt are modeled, that is a lot of data to store.

Another thing to look into would be setting the Use Shared Cell option in the last step of Create Symbol. Consider modifying the 3D symbols for your equipment (not variable or linear objects like cables and bus) and setting this option. You may want to backup your catalog(s) first, just in case.

After simplifying or setting a symbol to Use Shared Cell, it would be necessary to update the project with the new versions of the symbol. You may be prompted for this or you may need to use Update Symbol.