The evolution of DELTA differential algorithm:

The 17th May 2015 DELTA was born on the Gulden blockchain, its main purpose was to prevent the extremely long block times we would experience due to the combination of ASICs and Profit switching pools targeting the Gulden blockchain. Our community being predominantly new to Digital currencies were not miners and participated and contributed in other areas of Gulden.

The development of DELTA began at a time when our longest block times started breaching over 3 hours on some days and we were averaging 130 blocks per day.
The 6th May 2015 we experienced a 1086 minute (18.1 hr) block and 23 blocks in total for the day, 11 days before DELTA went live. Our community at the time invested in mining campaigns which provided dedicated hash and helped keep the blocks coming in until we crossed the DELTA line.

DELTA goes live:

It was a day of celebration and the positive effects were noticed immediately, 11 days after our worst blockchain performance our longest block time was 46 minutes and 371 blocks for the day was achieved. The Gulden blockchain could finally keep itself moving along without the need for serious amounts of dedicated hash.
While the first implementation of DELTA was a huge improvement and kept the blockchain moving without the need for any further mining campaigns, it was still far from perfect.
As a development team we were content with leaving DELTA in its current form so we could put energy and time into other projects we needed to get out the way and revisit the DELTA implementation at a later stage.

The growth spurt:

2016 was the year Gulden started seeing some serious growth in users especially in the last half of the year. With more users came more services and ultimately more demands on our blockchain. We started to experience an influx of support calls related to initial syncing issues brought about by > 30 minute block times which would self-correct once a block was found. The time had come to improve on DELTA to provide a better overall experience for our growing user base.

Real Gulden block numbers vs Expected numbers:

The 3 goals we needed to achieve with the next DELTA update was getting Gulden in line with the expected daily block numbers, reducing the longest block times and increased hash rate which adds additional security.
With the expected 150 second (2.5 min) block average it was important to aim for the around the perfect average of 576 blocks per day and at this stage we were averaging 420 blocks daily. Our longest daily blocks ranged from 34-50 minutes.

16th December 2016 the updated DELTA version went live:

It didn’t take long before we noticed that both our goals for this update had been achieved. A medium of around 576 blocks daily and 17 minutes became our new longest average daily block time, the improved performance was felt by services and existing users when transacting over our blockchain. This equated to a +-23% improvement in block numbers and a massive +-60% reduction in longest block times.
This resulted in a lot more mining power (hash rate) which in turn improves security and overall health of the Gulden blockchain.

The future for DELTA:

Our team strives for perfection and while we are happy with the current state of DELTA there is always ways to do things better. Part of this comes with our next major update, code named PRIME I which is expected end of March/April and more details about this project will be discussed closer to release.