NCBI announces the "better, faster, smaller" core_nt database to become the default from August:

From: NLM/NCBI List blast-announce <blast-announce@ncbi.nlm.nih.gov>

Interested in faster nucleotide BLAST searches with more focused search results? NCBI has been re-evaluating the BLAST nucleotide database (nt) to make it smaller and more efficient. Thanks to your feedback, we have created the core nucleotide database (core_nt), an alternative to the default nt database that contains better-defined content and is less than half the size.

Read more at NCBI Insights and try out the new database: https://bit.ly/46d49r8
https://bit.ly/46d49r8