A more recent link about tls 12
What version of ssis?

Regarding "I am ignoring all errors during this process"
May an error cropped up and a full batchsize was not imported? (bulk vs individual loads)

Do you have the create table and create index scripts?
Which indexes and in what fieldorder are those on [dbo].[IncidentFormSearchModel] ?
Does your used index  include IncidentStatus?
What version of...

Does is run in a virtualized environment? I had strange cases of VM ballooning denying memory for sql server

Can't find an option. Workaround: setup a job to (re)move old audit files?
C2 to be replaced with Common Criteria Compliance Enabled Server Configuration

see microsoft documentation

Readonly snapshots?
https://docs.microsoft.com/en-us/sql/database-engine/database-mirroring/database-mirroring-and-database-snapshots-sql-server?view=sql-server-2017

Read the link you've included about network io in your post.
Solutions:  revamp the application (select data, improve data handling)
It usually means that sql server is streaming data to...

added * for testing. Len +2 because len trims the rightmost whitespace.

declare @totrim varchar(50)='Reference Number: 878655555 detail, detail, lots of text etc'
declare @toskip varchar(50)='Reference Number:...

Regional settings of the reporting server?
You can alter the default language of a login with ALTER LOGIN

Regarding oracle tuning I refer to orafaq How to tune SQL or Identify Performance Problem and Bottleneck

Is it possible to tune the data driven query for your subscriptions, so it only returns persons who weren't in the previous dataset?

Trying to restore data for comparison (before & after) and find out the backupprocess missed the necessary archivelogs for a restore to time.
Luckily it could be reconstructed from other...

Mainstream vs extended support
If possible contact your MS person

Some recent blogs about parametersniffing
Parametersniffing 1
Parametersniffing 2
Parametersniffing 3