Improve memory usage #1163

Job	Run time
feature_set	4m 26s
format	6s
msrv	19s
examples	36s
rust-clippy-analyze	48s
test	1m 36s
udeps	47s
engine_io (v3)	27s
engine_io (v4)	30s
socket_io (v4)	32s
socket_io (v5)	33s
socket_io (v5-msgpack)	35s
adapter (v4, fred-e2e)	1m 13s
adapter (v4, redis-e2e)	1m 20s
adapter (v4, redis-cluster-e2e)	1m 13s
adapter (v4, fred-cluster-e2e)	1m 18s
adapter (v4-msgpack, fred-e2e)	1m 15s
adapter (v4-msgpack, redis-e2e)	1m 4s
adapter (v4-msgpack, redis-cluster-e2e)	1m 7s
adapter (v4-msgpack, fred-cluster-e2e)	1m 26s
adapter (v5, fred-e2e)	1m 39s
adapter (v5, redis-e2e)	1m 21s
adapter (v5, redis-cluster-e2e)	1m 7s
adapter (v5, fred-cluster-e2e)	1m 6s
adapter (v5-msgpack, fred-e2e)	1m 5s
adapter (v5-msgpack, redis-e2e)	1m 4s
adapter (v5-msgpack, redis-cluster-e2e)	1m 8s
adapter (v5-msgpack, fred-cluster-e2e)	1m 17s
all_passed	1s
	30m 59s

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