Improved Multiprocessor (SMP) Performance: The buffer manager for 8.1 has been enhanced to scale almost linearly with the number of processors, leading to significant performance gains on 8-way, 16-way, dual-core, and multi-core CPU servers.

Bitmap Scan: indexes will be dynamically converted to bitmaps in memory when appropriate, giving up to twenty times faster index performance on complex queries against very large tables. This also is designed to help simplify database management by greatly reducing the need for multi-column indexes.

Table Partitioning: The query planner is now able to avoid scanning whole sections of a large table using a technique known as Constraint Exclusion. Similar to the Table Partitioning found in other database management systems, this feature improves both performance and data management for multi-gigabyte tables.

Shared Row Locking: PostgreSQL's "better than row-level locking" now supports even higher levels of concurrency through the addition of shared row locks for foreign keys. Shared locks will improve insert and update performance on many high-volume OLTP applications.

Additional features include:

GiST: PostgreSQL's Generalised Search Tree (GiST) pluggable indexing mechanism has improved to support the high-speed concurrency, recoverability and update performance previously enjoyed only using B-Tree indexes. GiST is the backbone of PostgreSQL's full-text indexing (TSearch2), geospatial (GIS) and tree-structure indexing. With this enhancement, complex data types will perform well even on the largest high-availability applications.

COPY Refactoring: COPY has been refactored for up to 30% faster processing of bulk load data. Along with CSV load improvements, this makes loading large databases into PostgreSQL faster than ever.

64-bit Shared Memory: The buffer manager has been enhanced to utilize up to two terabytes of RAM on 64-bit platforms, preparing PostgreSQL for the high-memory servers of the future.