Having similar issues - appears that boats cause chunk loading to almost seize at times.

Noticed significantly lower chunk loading in 1.9 - combined with it being much more intensive too. (not sure if related to boat issue).

When it occurs, spamming in console such as:

[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 10.310490759107779,9.42605993259349E-10,0.11390929921253701
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 10.707463993554484,9.48517708820873E-10,0.11630037233589974
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 11.104739413636707,9.538112522022857E-10,0.1186440849378414
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 11.502286800781803,9.582024063092831E-10,0.1209451730701403
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 11.900078958276936,9.615632734494284E-10,0.1232078991815797
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 12.29809140908219,9.638725373406487E-10,0.12543609947533696
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 12.696302123860733,9.6520125225652E-10,0.12763322653336218
[07:51:35 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.4344326905447815,0.0,-11.621040390977214
[07:51:35 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.4700605283251207,0.0,-11.909678920081205
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 13.094691294838412,9.656915267441946E-10,0.12980238768068375
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 13.493241076388585,9.65506785632897E-10,0.1319425446126843
[07:51:35 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.5021255814790493,0.0,-12.169453589393015
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 13.891935407451456,9.648317700339248E-10,0.13405659775162349
[07:51:35 INFO]: Erynd issued server command: /tpaccept
[07:51:35 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.530984128552518,0.0,-12.403250785579075
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 14.290759833073025,9.638441156312183E-10,0.13614715747826267
[07:51:35 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.5569568202299706,0.0,-12.613668256573874
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 14.689701343793786,9.627072472540021E-10,0.13821657313565083
[07:51:35 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.5852324750085245,0.0,-12.842743157365476
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 15.088748231100908,9.615490625947132E-10,0.14026695912980358
[07:51:35 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.6155807965260465,0.0,-13.088609744530913
[07:51:35 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.647794518055889,0.0,-13.349588849032443
[07:51:35 WARN]: Boat (vehicle of Danielsom) moved too quickly! 15.4878899573323,9.604690376363578E-10,0.14230021842740825
[07:51:36 INFO]: Erynd issued server command: /tpaccept
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.2277699414917151,0.0,-9.94676444218021
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.2469390331643808,0.0,-10.102062623867823
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.2641912152139412,0.0,-10.24183098368303
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.2797181786481815,0.0,-10.36762250418542
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.293692445367924,0.0,-10.480834869638784
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.3062692850835447,0.0,-10.582725995847795
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.3224886734169559,0.0,-10.71412718891952
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.341986355419067,0.0,-10.872087441466647
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.3595342687549419,0.0,-11.014251664992116
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.375327390338498,0.0,-11.142199462776261
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.3895411993871676,0.0,-11.25735247773082
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.402333627193002,0.0,-11.360990188444703
[07:51:36 WARN]: Boat (vehicle of Magic_Pickle) moved too quickly! -1.4138468119126628,0.0,-11.454264125615737
[07:51:36 WARN]: Champ moved too quickly! -4.259839175680099,-1.8378585789729982,8.938532357316944
[07:51:36 WARN]: Steam_Is_Down moved too quickly! 4.814018034787296,0.0,8.98353055960979

Timings report INCREDIBLY high chunk load issues. http://timings.aikar.co/v2/?id=0b1fbb936dcd4c6184211b5ca6467165&section=lag

Would appreciate support with this issue and appreciate your efforts on the Spigot project immensely!