Counting PIC18F46K20 internal clock edges using MPLAB C18?
Timer 0 set up for a "delay" of 1 second sounds implausible unless you are using a very slow clock.

They way I usually create slow clock ticks (like 1 second) is to use timer 2 with its built-in period register to make a 1 ms clock tick.  That is still "slow" relative to how fast the PIC can run.  If the PIC is running at 10 MHz instruction rate, then the 1 ms interrupt will occur once every 10,000 insruction, which means it takes a tiny fraction of the processor's overal time.  Then you count multiple 1 ms periods in firmware to make various other clock ticks.

For example, you might count 100 of those to make a 100 ms clock tick, then 10 of those to make a 1 second clock tick.  Often several different internal clock tick rates are useful.  If you truly only need 1 second, then set up timer 2 to the largest sub-multiple of 1 second worth of instruction cycles it can manage, then count in firmware from there.