After upgrading to 1.24 we've experienced server crashing performance issues with filters including multiple entity references. I've reduced an example request down to what seems to be a minimal set of filters that lead to a timed out response.
?filter[status][value]=1
&filter[node--location][condition][path]=field_location.uuid
&filter[node--location][condition][value][]=1c28abaa-f088-404f-925f-263838332601
&filter[node--location][condition][operator]=IN
&filter[taxonomy_term--audience][condition][path]=field_event_audience.uuid
&filter[taxonomy_term--audience][condition][value][]=9422db2a-0071-4d3e-8b33-f3762c26fc19
&filter[taxonomy_term--audience][condition][operator]=IN
&filter[taxonomy_term--audience][condition][memberOf]=audience
&filter[audience][group][conjunction]=OR
&filter[parent][condition][path]=field_event_audience.parent.uuid
&filter[parent][condition][value][]=9422db2a-0071-4d3e-8b33-f3762c26fc19
&filter[parent][condition][operator]=IN
&filter[parent][condition][memberOf]=audience
I haven't been able to test this with 2.x yet as we're relying on consumer_image_styles at the moment and it does not appear to be compatible with 2.x. That's the next step but wanted to report this in case anyone has other ideas in the meantime.