Official statistics show 480 people spent more than eight hours in A&E last December, a 69% fall from 1,555 in December 2012.
The number waiting for more than 12 hours fell by 87% over the same period, from 323 to 42.
National standards state at least 98% of people in A&E should be admitted, transferred for treatment or discharged from hospital within four hours.
Across Scotland, 93.5% of people were dealt with within the required time in December, down from 94.7% in November.
Only five of Scotland's 14 regional health boards met the 98% target - NHS Fife, NHS Orkney, NHS Shetland, NHS Tayside and NHS Western Isles.
Health Secretary Alex Neil welcomed the drop in long wait times but insisted he was not complacent and would continue to work with health boards to improve performance.
He said: "That is why we introduced our three-year £50 million emergency care action plan, so that health boards can put in place a number of new measures to ensure we can cope with the added strain that winter can bring.
"Over £9 million of this money has already been released to health boards to support their planning, which is triple the amount given to boards for winter planning last year.
"Thanks to improvements already made through the action plan, I am encouraged that NHS boards have performed better in comparison to the same period last year, although I would still emphasise that any long waits are unacceptable.
"I am not complacent and we continue to work closely with health boards across Scotland to improve their performance."
The Scottish Government has set an additional milestone for 95% of patients to wait no more than four hours to be seen and treated by the year ending September 2014.
Across Scotland, the figure against this target was 93.6% for the year ending December 2013.