There is a lot to do at Port Aventura. Lots of shows etc
And a very good number of rides
The top 10 or whatever get big queues , from my experience but that’s August
We tended to do the evenings as it opens till midnight in the summer - not sure about April but if they have good hours that may help
As an example this was the queue board when we got their this summer at about 630 pm on a weekday
Other evenings were quieter though as the week went on