Searching is slow because it has to pause 60s between each search and on a given issue there could be up to 3 searches for that issue number (ie. 5, 05, and 005), along with if you have alternate search terms and/or different series naming conventions.
The 60s isn't changeable due to how indexers run their api's and tend to block out applications that hit them excessively fast, so it's to accommodate not hammering the sites. While 60s might seem abit much, so is hammering a site every single second - and all the searching is done in background threads so it shouldn't affect the usage otherwise
Now if you're taking about comicvine searches, again that's the CV api restrictions. They limit it to an api request every odd second and then a limited number per hour. Plus, their search methodology sucks so if you search for a general/common series, like 'batman' or whatever, it'll pull down the first 1000 hits out of ten thousand+. If you're searching for series that have multiple words, put the words in double quotes and it'll limit the search to that exact wording (ie. "Gotham city garage" will produce less results if done in double quotes)