If you have problems that are not addressed below, please do not hesitate to reach out to NCBI for help: blast-help@ncbi.nlm.nih.gov.

The initial BLAST search takes too long

The BLAST databases are fetched from the NCBI (located in the east coast of North America), so if your instance is running in a region that is geographically far from NCBI, you will likely experience lengthy BLAST download times. Please see how to choose a region.

BLAST takes too long

To run BLAST optimally, the BLAST database should fit in the host’s main memory (i.e.: RAM). Please see how to choose an instance.