If your contacts load slowly or never load in the ZynBit sidebar, it is because ZynBit now checks ALL fields with the data type of “Email”. ZynBit does this to check for duplicate contacts and makes it simple for you to interact with the right contact.
For Salesforce customers who have 2 or more “Email” fields AND/OR a large number of contacts, the initial contact query can take 2-4 seconds or even time out altogether. You can index each of your email fields in Salesforce to improve and speed up the performance. A Salesforce admin should do the following:
Open the Setup Menu and choose Customize -> Contacts -> Fields
Edit each email field and set the field as an External ID and click Save (as shown in the last line of this screen shot).
You should now see that the field is Indexed when looking at the field list as shown.