Game Loading Times

Slot Loading Times Across Operator Sites

First published on iGaming Business, 17 November 2017

The time a slot takes to load is a key customer service KPI in online casino. In this month’s exclusive analysis for iGaming Business, Ken Muir from iGaming Tracker analyses the loading performance of four popular titles from NetEnt, Play’n’Go, SG Interactive and Yggdrasil across six leading online casino sites – Bet365, LeoVegas, Mr Green, Sky Vegas, Unibet and William Hill.

One of the most common customer complaints in an online casino is that a game loads slowly or fails to load. The reasons behind slow loading times can be difficult to ascertain, as they can be many and varied.

It could be the customer’s bandwidth connection, it could be problems with the website or with the gaming platform hosting the game, or it could even be the game itself.

We work with clients to try and understand the scale of the problem and establish why it is happening. In this article, we will analyse the game loading times of four popular casino games – Play’n GO’s Book of Dead, SG Interactive’s Rainbow Riches Pick’n’Mix, NetEnt’s Starburst and Yggdrasil’s Vikings Go Bezerk, each launched from a different selection of four operator sites.

The operator sites used in this study were Bet365, LeoVegas, Mr Green, Sky Vegas, Unibet and William Hill.

To be clear, the analysis is only of the loading times of successful game loads; it ignores any failed attempts to load the game (we have found that generally 1-2% of load attempts fail).

As you can see from the table below, the games and sites tested are a representative mix of popular games and casino sites.

Test conditions
The tests were carried out between 4 November and 12 November, 2017 in a controlled environment with consistent bandwidth connection. This approach eliminates any issues with the customer’s bandwidth speed.

Testing the game over several sites helps us understand the performance of the gaming platform as well as of the individual casinos. By looking at the overall average game loading time, as well as the file size, we can understand the differences between the games and the sites.

How we performed the tests

  • Each time a game was launched, we tested it “uncached”, i.e. without browsing history/cookies, and “cached” where browsing history is present
  • For consistency, we used a ‘virtual machine’ with the bandwidth speed “throttled” at 32 MBps, emulating a typical broadband speed and ensuring each game test was using the same broadband speed
  • The games were launched in a mobile browser within the UK
  • We carried out at least 100 tests for each game, ensuring a comprehensive picture of game loading variations by day and hour
  • Loading times are defined as the time from clicking “play” to the time the game is ready for the customer to play
  • Game file sizes were recorded using Chrome developer console. The total cached and uncached file size was recorded

The results

  • ​File size vs. load time
    As you would expect, there is a direct relationship between the game file size and the game load time. However, there are games that under- and over-perform compared to their file size. The chart below clearly shows the different approaches games suppliers adopt with regards to the file size of their games.

Starburst by NetEnt has a small file size and consequently a short average loading time. Likewise, Book Of Dead has a relatively small file size and a proportionate loading time.

However, Vikings Go Bezerk has a much higher file size typical for Yggdrasil games, but the game loading time is much shorter than you would expect.

  • Cached vs. uncached load times
    The graph below shows the load times per test by game. The horizontal axis shows the loading time on an uncached browser, while the vertical axis shows the second part of the test, testing the game loading time with the game cached in the browser.In the tests, we throttled the bandwidth speed to a typical home broadband speed to make the tests realistic and consistent. As you can see, there are different time distributions for each game. This seems to have affected Rainbow Riches Pick’n’Mix to a significant degree.

  • Casino site performance
    As we have seen, there is a direct relationship between file size and game loading time. However, the operator site also affects the performance, and our testing the games on different sites produced some interesting results.

Book of Dead – Bet365 gave consistently better loading times for this game, with Leo Vegas, Mr Green and Unibet clustered closer together.

The graph below clearly shows the amount of ‘outliers’, where a significant proportion of game loads resulted in abnormal load times. Unfortunately, this is not unusual.


Starburst – as with Book Of Dead, Bet 365 has consistent and short loading times, as does Leo Vegas. At the other end of the spectrum, William Hill has slightly longer and more erratic loading times.

Vikings Go Bezerk – this Yggdrasil game has much more consistent loading times than others, although they are longer due to their file size. The game loading times between the various casinos do not seem to differ to any degree.

Rainbow Riches Pick’n Mix – this SG Interactive game possesses a large file size, and the LeoVegas and Bet365 sites seemed able to handle this better than William Hill.

The results for Sky were also much higher for the same test. This level of performance is not typical for Sky Vegas based on the tests we performed for other games on the site, but the large file size of this particular game and the bandwidth speed seems to have affected Sky Vegas disproportionately more than the other casinos.

Summing up
This analysis took in a small sample of games across a small sample of online casinos. However, it does illustrate that on a key customer service KPI – the time a slot takes to load – marked differences exist between games and casinos.

Some may say it’s only a matter of few seconds and the games always end up loading anyway, but these differences give a strong indication of the attention developers and casinos pay to their service levels.

On this basis, it is therefore not surprising that the shortest and most consistent loading times are for the most popular slot game, Starburst, on the most popular website, Bet365.

iGaming Tracker – how it works
iGaming Tracker tracks hundreds of casino sites worldwide every day. From this data it can ascertain which games are on which sites and where they are positioned on the pages. It can also measure the market share of casino games suppliers by percentage of “real estate” on casino sites at any given date.

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