Sergiy,

There is always the 'It depends' caveat when looking at the this type of thing, and in a lot of cases the actual table design is the issue, especially if its very wide, and full of verbose data (VARCHAR fields).

Sorting out the indexes is probably the first place to start see where if there are still issues with performance.

Something as simple as an Index defrag/rebuild routine, if one doesnt exist already, can give a significant boost to the performance.

After that its about looking at unused indexes and removing them, and you'd be surprised how many developers create indexes that are virutally the same thinking they perform better.

The other possibility is that the infrastructure needs to be looked at, especially if its never switched servers.