If you are an active Gmail user then you’ll have probably noticed that it often takes 3+ seconds for Gmail to search my inbox, and it usually takes less than 1 second for Google to return results for a search query on the web. Do you know why is there this much speed difference? 🙄 🙄

Gmail Inbox Search is slower than Google Web Search.

Gmail Inbox Search is slower than Google Web Search.

Some Reasons for the Speed Difference

Most simply, it is because Gmail Search is not parallelized the way Web Search is (both because of architecture & the problem spaces). It’s not a technical impossibility to overcome, but a matter of resource optimization.

Here are some other factors that also make mail search harder than web search in some ways :

  • The total contents of the web is actually smaller than the sum of the sizes of the contents of everyone’s Gmail. This means it could take more servers to hold all the indexes for mail search than for web search.
  • When you search the web, for the most part, you’re getting the same results for your query as anyone else would get for that query. This means caching works well for web search. Most search engines have a small “hot index” with the most popular content that can handle the majority of queries which is replicated out to lots of local datacenters, giving low average response time even if the worst case is slow.
  • Gmail search results are sorted by time and need to be perfect matches, whereas web search results are sorted by relevance and approximations can be made to cut corners.