Address performance regression in vote_cache::top #1927

Job	Run time
Linux [UBSAN] [lmdb \| clang]	38m 2s
Linux [ASAN] [lmdb \| clang]	37m 38s
Linux [ASAN_INT] [lmdb \| clang] (Errors Ignored)	37m 55s
macOS [UBSAN] [lmdb \| clang]	35m 12s
Linux [TSAN] [lmdb \| clang]	39m 11s
macOS [ASAN] [lmdb \| clang]	29m 43s
Linux [LEAK] [lmdb \| clang] (Errors Ignored)	39m 20s
macOS [TSAN] [lmdb \| clang]	29m 37s
Linux [UBSAN] [rocksdb \| clang]	43m 57s
macOS [UBSAN] [rocksdb \| clang]	36m 25s
Linux [ASAN] [rocksdb \| clang]	48m 54s
macOS [ASAN] [rocksdb \| clang]	37m 57s
Linux [ASAN_INT] [rocksdb \| clang] (Errors Ignored)	48m 53s
macOS [TSAN] [rocksdb \| clang]	47m 51s
Linux [LEAK] [rocksdb \| clang] (Errors Ignored)	47m 30s
	9h 58m 5s

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