SQL Server 2012 :: Avoiding Temp Table With String Of IDs Passed Into Stored Procedure

Using a string of IDs passed into a stored procedure as a VARCHAR parameter ('1,2,100,1020,') in an IN without parsing the list to a temp table or table variable. Here's the situation, I've got a stored procedure that is called all the time. It's working with some larger tables (100+ Million rows). The procedure passes in as one of the variables a list of IDs for the large table. This list can have anywhere from 1 to ~100 IDs passed to it.

Currently, we are using a function to parse the list of IDs into a temp table then joining the temp table to get the query:

CREATE PROCEDURE [dbo].[GetStuff] (
@IdList varchar(max)
)
AS
SET NOCOUNT ON
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

[Code] .....

The problem we're running into is that since this proc gets called so often, we sometimes run into tempDB contention that slows this down. In my testing (unfortunately I don't have a good way of generating a production load) swapping the #table for an @table didn't make any difference which makes sense to me given that they are both allocated in the tempDB. One approach that I tried was that since the SELECT query is pretty simple, I moved it to dynamic SQL:

CREATE PROCEDURE [dbo].[GetStuff] (
@IdList varchar(max)
)
AS
SET NOCOUNT ON
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

[Code] ....

The problem I had there, is that it creates an Ad Hoc plan for the query and only reuses it if the same list of parameters are passed in, so I get a higher CPU cost because it compiles a plan and it also causes the plan cache to bloat since the parameter list is almost always different. Is there an approach that I haven't considered that may get the best of both worlds, avoiding or minimizing tempDB contention but also not having to compile a new plan every time the proc is run?