V/Line's latest performance figures show 90 per cent of trains ran on time in December, a three per cent drop from the month before.

It was the first time the service failed to meet its 92 per cent target since March that year.

But the slight performance drop didn't stop the Warrnambool train line from recording its best yearly performance on record.

There were eight consecutive months above target in 2020 - a win for the city's passengers who have struggled through years of slow trains.

Warrnambool's train service exceeded its punctuality target just two times in the last two years, and 12 times between 2009 and 2019.

But the number of people there to appreciate the feat was limited with the increase in on-time trains correlating with a drop in patronage due to the coronavirus pandemic.

When the virus brought the world to a halt in March, trains continued to run as normal but the state's public transport network saw patronage reduce by more than 90 per cent compared to usual levels due to lockdowns and restrictions.

In August, when 97.1 per cent of trains ran on time, patronage was as low as five per cent of normal levels.

Then when punctuality decreased slightly in December, patronage had returned to between 50 and 65 per cent.

A V/Line spokesman said the transport service was "working hard to maintain the strong performance results recorded during 2020 as we welcome more passengers back to the network in the new year".

He said there were several unrelated factors which contributed to December delays on the Warrnambool line including infrastructure and train faults, an emergency services request and an instance where livestock entered the rail corridor.

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