Measure Calculations are Really Slow

Hey everyone, I have several measures that I'm using that are really slowing my report down. Wondering if any of you can provide any tips to make them more efficient.

ARR (Monthly) = 
VAR LastInvoice =
    CALCULATE(
        MAX(Invoice[Invoice Date]),
        DATESBETWEEN(
            'Calendar'[Date],
            CALCULATE(
                MIN('Calendar'[Date]),
                ALL('Calendar')
            ),
            LASTDATE('Calendar'[Date])
        )
    )
VAR NextInvoice = 
    CALCULATE(
        MIN(Invoice[Invoice Date]),
        DATESBETWEEN(
            'Calendar'[Date],
            LASTDATE('Calendar'[Date]),
            CALCULATE(
                MAX('Calendar'[Date]),
                ALL('Calendar')
            )
        )
    )
RETURN
IF(
    CALCULATE(
        SUM(Invoice[ARR Amount]), 
        Invoice[Months]=1
    ) = 0,
    IF(
        CALCULATE(MAX(Invoice[Months]),DATESBETWEEN('Calendar'[Date], LastInvoice, LastInvoice))<>1,
        0,
        IF(LastInvoice = 0 || NextInvoice = 0,
            0,
            CALCULATE(
                SUM(Invoice[ARR Amount]),
                DATESBETWEEN(
                    'Calendar'[Date],
                    LastInvoice,
                    LastInvoice
                )
            )
        )
    ),
    CALCULATE(
        SUM(Invoice[ARR Amount]), 
        Invoice[Months]=1
    )
)

Which is referenced in:

ARR (Monthly Summed) = 
VAR CustomerList = VALUES(Customer[Customer ID])
VAR Result = SUMX(CustomerList, _Measures[ARR (Monthly)])
RETURN
Result

Which is referenced in:

ARR (Invoices) = 
[ARR (Monthly Summed)]
+
CALCULATE(
    SUM(Invoice[ARR Amount]),
    Invoice[Months] = 3,
    DATESBETWEEN(
        'Calendar'[Date],
        EOMONTH(LASTDATE('Calendar'[Date]),-3)+1,
        LASTDATE('Calendar'[Date])
    )
)
+
CALCULATE(
    SUM(Invoice[ARR Amount]),
    Invoice[Months] = 6,
    DATESBETWEEN(
        'Calendar'[Date],
        EOMONTH(LASTDATE('Calendar'[Date]),-6)+1,
        LASTDATE('Calendar'[Date])
    )
)
+
CALCULATE(
    SUM(Invoice[ARR Amount]),
    Invoice[Months] = 12,
    DATESBETWEEN(
        'Calendar'[Date],
        EOMONTH(LASTDATE('Calendar'[Date]),-12)+1,
        LASTDATE('Calendar'[Date])
    )
)
+
CALCULATE(
    SUM(Invoice[ARR Amount]),
    Invoice[Months] = 36,
    DATESBETWEEN(
        'Calendar'[Date],
        EOMONTH(LASTDATE('Calendar'[Date]),-36)+1,
        LASTDATE('Calendar'[Date])
    )
)

ARR (Subscriptions) = 
CALCULATE(
    SUM(Subscriptions[Net ARR]),
    Subscriptions[Subscription Status] = "live"||
    Subscriptions[Subscription Status] = "dunning" ||
    Subscriptions[Subscription Status] = "non_renewing" ||
    Subscriptions[Subscription Status] = "paused" ||
    Subscriptions[Subscription Status] = "unpaid"
)

Which both are referenced in:

ARR = 
VAR MaxDate = CALCULATE(MAX('Calendar'[Date]))
RETURN
IF(
    MaxDate = EOMONTH(TODAY(), 0),
    [ARR (Subscriptions)],
    IF(
        MaxDate > EOMONTH(TODAY(),0),
        0,
        [ARR (Invoices)]
    )
)

@lbendlin Thank you for your response. Unfortunately, I'm not advanced enough to know how to utilize your suggestions. So here is some more context.

Here are the tables being used:

Invoices

Subscriptions:

The reason why we use both tables is because we can get historical ARR from the invoices, but we have to use the Subscriptions table to get ARR for the current month. So the ARR measure calculates ARR for each customer each month. If the month in context is before today's month, then it uses ARR calculated from the Invoices table, otherwise it uses ARR from the subscriptions table.

The ARR (Invoices) Measure is calculated by taking the ARR (Monthly Summed) measure (I'll talk about this in depth next) and adding it to the sum of ARR for each interval subscription. This is important because a 12 month subscription only has an invoice created every 12 months. So we have to find the sum of ARR in the last 12 months for each customer with 12 month subscriptions. Same logic is applied to 3 month subscriptions etc.

To add further complexity, sometimes monthly subscriptions aren't billed every month (e.g. we gave a customer a free month for whatever reason). The ARR (Monthly) measure checks if the month's ARR amount is 0. Then it checks if the customer had an invoice prior to the month in context and after the month in context. If that's true, then it takes the most recent ARR amount and holds it equal to the current month. The ARR (Monthly Summed) is a SUMX, so it can be analyzed on the customer level.

The ARR measure is being calculated in a way that it can be analyzed on a customer level, so we can find upgrades/downgrades in each month. The desired outcome would be the ability to make a matrix calculating ARR for each customer like this:

Thank you for your help with this. Let me know if you have any additional questions or if I can clarify anything.

The report is borderline unusable currently, but the numbers are correct. I presume there must be a better way. Thank you in advance for any help you can give!

mahoneypat any ideas?