Can i delete relation of table ?

If I delete relation of table NopSystem will lost performance ?
and I have Product more 40k page load 20sec
how to tunning performance Please tell me .

What exactly relation do you want to delete?
What version are you using?

a.m. wrote:
I'm using Nop V.2.3
I'm delete relation of table{
Category,Product,
Product_Category_Mapping,
Product_Manufacturer_Mapping,
Product_Picture_Mapping,
Product_Picture_Mapping
Product_ProductTag_Mapping,
Product_SpecificationAttribute_Mapping,
ProductVariant,
SpecificationAttribute,
SpecificationAttributeOption
and any
}
if i delete it NopSystem2.3 will lost performance ?
Because I want update data of product not relation table

It will lose stability because some of these relations are configured for cascade deletion.

Ok thanks ,
and I have one question
About Performance
I'm used MSSQL2005 and IIS7
total product 40k my website very slow 20sec/page.
How to tunning performance it?
First i'm testing StroeProcedure of V2.5 it same slow.

Please suggestions or the best way of tunning performance?
Please tell me

You can disable some not used features and remove unused functionality. For example, go to admin area > configuration > settings > catalog settings > "Ignore tier prices (sitewide)", "Ignore discounts (sitewide)", "Ignore featured products (sitewide)", etc.
P.S. There're a lot of topics about other performance tips on these forums