QB Issue Resolution:
FWIW, the original issue was caused by a change in performance characteristics in the OS. A fix went out in R6 (long ago) to use larger “packet” sizes which caused a large increase in speed on Mavericks for this particular problem.
Resolution for Issue 'Extremely slow server connection with Quickbooks Pro Mac 2014' available: Yes (Solved).
Source: Intuit Community forum.
Extremely slow server connection with Quickbooks Pro Mac 2014: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.Support for Quickbooks
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