Speed up header check

[ucwong]

No description provided.

[codecov]

Codecov Report

Merging #871 (4a3f9f4) into master (6118859) will increase coverage by 0.04%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master     #871      +/-   ##
==========================================
+ Coverage   49.25%   49.30%   +0.04%     
==========================================
  Files         420      420              
  Lines       48058    48058              
==========================================
+ Hits        23672    23693      +21     
+ Misses      22315    22294      -21     
  Partials     2071     2071              

Impacted Files	Coverage Δ
ctxc/backend.go	0.00% <0.00%> (ø)
ctxc/downloader/statesync.go	56.20% <100.00%> (-4.27%)	⬇️
consensus/cuckoo/cuckoo.go	30.86% <0.00%> (-4.94%)	⬇️
ctxc/downloader/downloader.go	76.36% <0.00%> (-0.43%)	⬇️
trie/proof.go	73.33% <0.00%> (+0.33%)	⬆️
p2p/simulations/http.go	66.66% <0.00%> (+0.64%)	⬆️
p2p/discover/v5_udp.go	81.06% <0.00%> (+0.79%)	⬆️
core/tx_pool.go	73.43% <0.00%> (+1.02%)	⬆️
p2p/simulations/mocker.go	28.86% <0.00%> (+1.03%)	⬆️
... and 4 more