Search faster with operators
Instead clicking on 'Show search options', you can type queries in the search box at the top like
to:email@example.com -- for the mails sent to firstname.lastname@example.org,
from:robin -- for the mails from robin,
subject:gems -- for mails with 'gems' in subject, etc.
You can do any "Search Options" search, and then look in the green header bar above the conversation list for the line that says "Search results for: ...". The bold text in that line is what you should type into the regular search box to get the same results.