Changing indexes will not improve the performance of a full table scan query (since,
with any luck, the index isn't being used; if your layer envelope is misconfigured,
indexed access will slow full table scan performance). Multi-level indexes will
usually hurt performance on layers with a normal distribution of feature extents.
If you have scale dependency set so that only a small portion of the table is being
displayed and it's still slow, one possibility is that the data is spatially fragmented
(neighboring features are nowhere near one another in the table, causing wasted
I/O to read pages and ignore most of the data). Changing indexes will not help
in this situation either, since the inefficiency is inherent to the table organization.
- V