Calculate A Range Bar From (stock) Tick Prices?

Assume you have a table called Tick with 2 columns
(
tickId bigint IDENTITY(1,1)
, price int -- usually money data type, making it int for simplicity
)

I am tasked with creating bars that are 10 units long.

Now the catch is I'm not looking for the tickId where price is >= t1(price) + 10 where t1(price) is the price for the first row where tickId = 1. (it could also be where price <= t1(price) - 10)

Here is sample data:

1, 25
2, 26
3, 23
4, 26
5, 27
6, 30
7, 34
8, 32
9, 30
10, 33

What I am looking for are rows 3 (23) and 7 (34)

Currently I have:

Code:
DECLARE @tickDiff int
SET @tickDiff = 10
DECLARE @r1TickId bigint

[Code].....

This seems to work but it is taking multiple minutes to run for about 50k rows of data (which I created off of the 24 million row table I have just looking at data from today). So it takes ~5 minutes to create the first bar which is not acceptible.

If my logic above seems acceptable are there any indexes you could recommend. Database engine tuning advisor didn't find any.