Actually, I won't give you the direct answer, but I'll tell you what I would do in such a case. Start with joining two tables (event_log, events). No conversion, no other tables, no ordering. Then step by step add other tables, then apply other criteria, ordering, conversion, etc. Which change decreases your query performance, focus on that change and try to see how to improve it. (or ask here :))
for example:
1- test this:
SELECT el.id, el.db_datetime, el.local_datetime, e.name
FROM event_log el
JOIN [events] e ON el.event_id = e.id
2- if it is ok, then test this:
SELECT el.id, el.db_datetime, el.local_datetime, e.name, sc.title
FROM event_log el
JOIN [events] e ON el.event_id = e.id
JOIN subcampaigns sc ON el.subcampaign_id = sc.id
...
step by step, improve your query.
Another option is to check execution plan. You can do this by right-clicking on the query within SSMS. Here is a good info on the subject:
Displaying Graphical Execution Plans (SQL Server Management Studio)[
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