Problem

ResponseChain memory usage causes OOM in nuclei when scanning critical severity templates (projectdiscovery/nuclei#6567). Profile analysis shows 6.73GB allocs during 300 reqs scan.

Analysis

3 alloc hotspots identified:

• fullResponse duplication (1.04GB, 15%): Headers+body duplicated in Fill() and held until Close() even when unused.

• Pool pollution: Buffers >2MB returned to the pool, causing small requests to reuse 8MB buffers allocated for large responses.

• String conversions (3.78GB, 55%): (*ResponseChain).Body().String() and (*ResponseChain).FullResponse().String() creates copies that outlive Close().