capsule_export.rb

  def change_token
    next_token = tokens.rotate!.first
    CapsuleCRM.configure do |config|
      config.api_token = next_token
    end
  end

  def get_classes
    CapsuleCRM.constants.map do |sym|
      CapsuleCRM.const_get(sym)
    end
  end

  def process_objects
    get_classes.each do |klass|
      next unless klass.respond_to?(:all)
      logger.info("Start export #{klass.to_s}")
      name = klass.to_s.gsub('CapsuleCRM::', '') + '.json'
      write_json(name: name, klass: klass)
      extract_closed_tasks if klass = CapsuleCRM::Task
      logger.info("Stop export #{klass.to_s}")
    end
  end

  def write_json(name:, klass:)
    file = create_file(name: name)
    klass.all.each do |klass_member|
      begin
        file.write "#{klass_member.to_json}\n"
        extract_info(klass_member)
      rescue CapsuleCRM::Errors::InternalServerError
        logger.info("Token switch")
        change_token
        extract_info(klass_member)
      rescue => e
        logger.error(e.message)
        # logger.info("#{klass} #{klass_member.id}")
      end
    end
    file.close
  end

  def create_file(name:)
    File.open(name, 'a')
  end

  def extract_info(item)
    extract_contacts(klass_member)
    extract_additional_info(klass_member)
  end


  def extract_contacts(person)
    return unless person.class == CapsuleCRM::Person
    file = create_file(name: "Contacts.json")
    contact_list = JSON.parse(person.contacts.to_json).delete_if { |_k, v| v.empty? }
    contact_list.each do |_key, contact_type|
      contact_type.each do |object|
        object.merge!('person_id' => person.id)
      end
    end
    file.write("#{contact_list.to_json}\n")
    file.close
  end


  def extract_additional_info(item)
    %i(histories tags custom_fields).each do |method|
      next unless item.respond_to?(method)
      file = create_file(name: "#{method.to_s.capitalize}.json")
      item.send(method).each do |object|
        file.write "#{object.to_json}\n"
      end
      file.close
    end
  end

  def extract_closed_tasks
    file = File.open('Task.json', 'a')
    i = 0
    size = 1000
    begin
      result = HTTParty.get("https://brandandcelebrities.capsulecrm.com/api/tasks?status=COMPLETED&start=#{i}&limit=1000",
        basic_auth: {username: "#{token}", password: "x"},
        headers: { 'Accept' => 'application/json' } )
      if result['tasks']['task'].present?
        result['tasks']['task'].each do |task|
          file.write("#{task.to_json}\n")
        end
        size = result['tasks']['@size'].to_i
        i += 1000
      else
        size = 0
      end
    end while size > 0
    file.close
  end

p CapsuleCRM::Case.all.first
p CapsuleCRM::Opportunity.all.first

# CapsuleImporter.new.process_objects

When you call CapsuleCRM::Opportunity.all.first CapsuleCRM retrieves all opportunities ( a very long request ) and after get the first one.
However if you try CapsuleCRM::Opportunity.first, it'll respond quickly.

I made a test and called CapsuleCRM::Opportunity.all I got a response after 1 hour.