Previous versions of the HubSpot-Salesforce integration relied heavily on custom Salesforce objects and Apex code to facilitate the sync between HubSpot and Salesforce. Most of the changes from versions pre-2.60 and versions post-2.60 don't affect the behavior of the sync in any functional way, but the changes reduce the amount of data storage required for the HubSpot managed package, reduce the overal number of daily API calls, greatly reduce the number of custom objects, reduce the amount of Apex code, and eliminate issues related to Salesforce governor limits. The reductions are aimed to be more considerate of Salesforce-side quotas and limits that HubSpot-Integrated Salesforce users may have run into through normal use of the integration.
The new connector still requires a managed package and one custom obect (object API name: HubSpot_Inc__HubSpot_Intelligence__c) to serve the HubSpot Intelligence VisualForce pages on Salesforce lead and contact layouts. If you are upgrading your HubSpot-Salesforce integration from a version pre-2.60, all HubSpot custom objects (with the exception of the HubSpot Intelligence object) will be deprecated and can be deleted entirely from your Salesforce organization. You can delete these objects from the Objects settings of your Salesforce environment (usually in Setup > Create > Objects). After the upgrade to 2.60, any object with a 'Del' option can be deleted; you will not be able to delete the HubSpot Intelligence object.
Important Note Regarding HubSpot Activities
The HubSpot Activity object will be deprecated and is no longer supported on versions of the managed package later than 2.60. If you are syncing HubSpot Activites to the HubSpot Activity object (object API name: HubSpot_Inc__HubSpot_Activity__c ), the integration will continue to sync HubSpot Activity records, however we recommend syncing Form and Email interactions (sent/opened/clicked) as Salesforce Activities. Using the Salesforce's native activity type allows for more flexible reporting by default and saves on data storage within Salesforce. For more information, please see this section of our Salesforce integration user guide.