It's always hard looking back and remembering timelines accurately but in the early days of Chrome coming on the scene, it did deliver significant improvements over Firefox of the time - the UI was much slicker and wasted significantly less screen space, it ran and loaded pages measurably faster (it would open twice as fast and load pages twice as fast), RAM management was better in Chrome, it was (afaik) first of the two to split tabs into separate processes, in the late 2000s and early 2010s Firefox was often more prone to breaking extensions during updates, Chrome updated more frequently and more routinely delivering security improvements, etc. etc.
Firefox has absolutely caught back up but there was definitely a period around 2010-2012 where they really fell behind quite significantly, Chrome gathered momentum and Firefox was never really able to reverse that shift in momentum.