I am having difficulty opening SpiReport. Even when I was still able to open it, it would take several hours to open a simple label design. Has anyone else struggled like this, and do you know how to solve the problem?
To echo my reply via email to your inquiry 
It sounds like it could be a device-specific issue– could you provide some information about the system (operating system, memory, etc.) you are using?
Is the app not opening or is the report opening very slowly?
When working with a local version of Specify 6, you should be able to edit reports and labels quickly. However, if you’re connecting to a remote server via SSH, slow speeds can be expected. Have you tried to edit reports/labels using SpiReport on a local copy of your database?
Thank you for posting it here as well! 
I’m using Windows 10 Pro on a machine with plenty of RAM (in any case, I can open all the other Specify apps). I have always struggled to open SpiReport and to open label designs (they always take several hours to open).
From our e-mail conversation, but sharing here so others can see it as well if needed in the future. 
Thank you for sharing a copy of the database! This allowed me to debug the issue and find a solution.
In your database, there are three queries that have invalid ContextTableIdent IDs.
When running the application from the terminal, I found the following error:
15:23:32 DEBUG specify.dbsupport.RecordTypeCodeBuilder:138 - retrieving TypeCode Fields for edu.ku.brc.specify.datamodel.Locality
15:23:32 ERROR core.db.DBTableIdMgr:527 - Couldn't find tableId[0] java.lang.NullPointerException at edu.ku.brc.specify.tasks.subpane.qb.QueryBldrPane.getColumnInfoSp(QueryBldrPane.java:2649)
The Couldn't find tableId[0] error indicated that the table ID being read by iReport was invalid, so I then investigated where the table ID came from. After reviewing all of the queries in the database and recognizing that the table IDs were valid, I checked several other places before finding that there were a handful of query field records that had invalid table IDs associated with them (contained in the ContextTableIdent field).
To resolve this, I ran the following SQL statement on the database:
update spqueryfield set ContextTableIdent = NULL where ContextTableIdent = 0;
The ContextTableIdent is set to NULL by default when created in Specify 7, as it is not necessary for queries to function.
After testing each of the queries that previously had fields with a ContextTableIdent of 0, I was able to run and use them without any issue.
iReport is now functioning properly for me!