"By default, SharePoint will only process 8 lookup columns in response to a query. The SharePoint server blocks queries that exceed this threshold rather than providing an incomplete response."
"You may get this error for a list that appears to contain fewer lookup columns than the threshold allows. This is due to hidden lookup columns associated with certain data types.
For example, if a list column is using the Managed Metadata content type, the list will include the hidden lookup columns TaxCatchAll and TaxCatchAllLabel, which perform lookups to a system taxonomy list.
Because these columns do not appear in the column list, it may appear that you are below the lookup column threshold after you have exceeded it."
Unfortunately SQList cannot bypass the threshold set on the lookup columns; this is not due to limitation of the product but rather a constraint of SharePoint itself and, therefore, its web services.
If the list requires all those look-up columns, the only workaround is to increase the threshold in "Central Admin".
In that case, as far as SQList is concerned, changes in performances could be noticed if large numbers of items in the list are updated very often. If that is not the case, SQList should not be particularly impacted, nor put excessive pressure on the server.