Help me with formulas

[Sench4]

I have a table named TestFormula Where are stored 50000 records.And table Parameters where are stored parameters of formulas :

TestFormula Parameters
Id Formula Value Id Parameter Value
1 a+b-c NULL 1 a 10
2 a*c - b NULL 2 b 20
..................................... 3 c 5
.....................................

Can anyone help me with technique to UPDATE TestFormula table's Value field with
his real value. I have a such technique but it lasts over 50 seconds. I need better technique.

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Thanks