What makes heroku response time too much slow

I would try to add NewRelic Heroku add-on, it will show you what takes the most time, most likely it will be your Ruby code doing HTTP requests in a controller action to crawl a page.

Heroku tends to be slower than running code on your own development machine because Heroku resources are shared across users unless you bought expensive M/L dynos.

Without you sharing the code for crawling we don't know much how it work and where is the bottleneck. Do you crawl the single page or many pages (then this might be slow).

You can try moving crawl logic to the background worker, for instance, use Sidekiq gem. You could crawl page from time to time and store results in your DB then your controller action would only ask for data from your DB instead of crawling page every time. You can also use a rake task every 10 minutes defined in Heroku Scheduler to crawl page instead of Sidekiq (this might be faster to do). I don't know if having data up to date every 10 minutes is good enough for your use case. You need to pick a tech solution for your business use case needs. With Sidekiq you could run jobs more often by starting them every 1 minute using clockwork gem.