Delay Between End of Root Task and Start of Dependent Task

I'm using a series of streams and tasks to extract, load, and transform raw data from our ERP system to Snowflake. I'm noticing a 2+ minute delay between when the root task completes and when the next dependent task starts. Each task calls an SQL stored procedure and completes in less than 5 seconds, so I though everything would complete in under a minute. There are a few other queries running at the same time, but they all complete in less than 5 seconds too and nothing that would explain such a long delay. Warehouse usage doesn't indicate being overloaded. Here's the sequence:

• Task 1 runs every 5 minutes using COPY INTO to move files from internal table stage to raw data table.

• Stream 1 records inserts only on the raw data table.

• Task 2 depends on Task 1 using MERGE INTO to transform and move records from stream 1 to the current data table.

• Stream 2 records inserts / updates / deletes on the current data table.

• Task 3 depends on Task 2 using MERGE INTO to move records from stream 2 to the historical data table.

Here's a copy of the activity log from Snowflake:

Any ideas what could be causing this delay? Or have I overlooked something?