Below is a chart showing the distribution of the top 100 Twitter accounts based on lists shows that Justin Bieber does make up a significant proportion of resources compared to any of the other top 100 Twitter accounts. It seems likely that he could in fact account for 3% of twitter's server usage but will the rise of more celebrities decrease his share based on % or will more fans who join Twitter follow him keeping his lead.It's interesting to see that some of the top 20 twitter profiles by lists subscribers feature a number of commercial businesses such as CNN, New York Times and Google, so how much support or priority will Twitter continue to provide these firms as the Twitter user base continues to grow? Twitter still is not monetising its platform as much as it can and outside Google what is the cost/benefit for continuing to support some of these power users who use around 14.4% of Twitters server capacity.The chart below shows the estimated breakdown of Twitter resources used with a % calculated based on list subscriptions, its interesting to see that some of the original power accounts like Ashton Kutcher & Britney Spears or even Oprah Winfrey have failed to keep pace with the pop stars like Justin Bieber or Lady Gaga.The most consistently reliable metric seems to be attributed to engagement calculated by platforms such as Klout or Twitalyzer rather than a pure focus on sheer follower numbers. Justin Bieber gets a perfect score of 100 with Klout and is noted as being in the top 99.9th percentile on Twitalyzer but has not improved his score in the last 30 days. I've taken some screen shots of the top 4 Twitter accounts based on the number of list subscriptions and it does show that even Klout struggles to calculate their true impact/reach.Even with Klout's missing metrics it still seems that a combination of List subscriptions and Klout score that you can estimate the true power of a Twitter user. Just with a glance of the 4 profiles you can be fairly confident that your Klout score is a much better metric for calculating both the importance of your Twitter account and its impact both on network reach and potential impact on Twitter resources. It's likely that celebrities will continue cause a strain on the platforms resources even with specific servers allocated for high profile accounts their reach will continue to impact on the standard accounts due to the over reach via Twitter lists.