diff --git a/electrum/submarine_swaps.py b/electrum/submarine_swaps.py
index 540102de2..778891526 100644
--- a/electrum/submarine_swaps.py
+++ b/electrum/submarine_swaps.py
@@ -11,7 +11,7 @@ from .crypto import sha256, hash_160
 from .ecc import ECPrivkey
 from .bitcoin import (script_to_p2wsh, opcodes, p2wsh_nested_script, push_script,
                       is_segwit_address, construct_witness)
-from .transaction import PartialTxInput, PartialTxOutput, PartialTransaction, Transaction, TxInput
+from .transaction import PartialTxInput, PartialTxOutput, PartialTransaction, Transaction, TxInput, TxOutpoint
 from .transaction import script_GetOp, match_script_against_template, OPPushDataGeneric, OPPushDataPubkey
 from .util import log_exceptions
 from .lnutil import REDEEM_AFTER_DOUBLE_SPENT_DELAY, ln_dummy_address
@@ -92,7 +92,15 @@ class SwapData(StoredObject):
     funding_txid = attr.ib(type=Optional[str])
     spending_txid = attr.ib(type=Optional[str])
     is_redeemed = attr.ib(type=bool)
-    _funding_prevout = None # for RBF
+
+    _funding_prevout = None  # type: Optional[TxOutpoint]  # for RBF
+    __payment_hash = None
+
+    @property
+    def payment_hash(self) -> bytes:
+        if self.__payment_hash is None:
+            self.__payment_hash = sha256(self.preimage)
+        return self.__payment_hash
 
 
 def create_claim_tx(
@@ -135,8 +143,14 @@ class SwapManager(Logger):
         self._max_amount = 0
         self.wallet = wallet
         self.lnworker = lnworker
+
         self.swaps = self.wallet.db.get_dict('submarine_swaps')  # type: Dict[str, SwapData]
-        self.prepayments = {}  # type: Dict[bytes, bytes] # fee_preimage -> preimage
+        self._swaps_by_funding_outpoint = {}  # type: Dict[TxOutpoint, SwapData]
+        self._swaps_by_lockup_address = {}  # type: Dict[str, SwapData]
+        for payment_hash, swap in self.swaps.items():
+            self._add_or_reindex_swap(swap)
+
+        self.prepayments = {}  # type: Dict[bytes, bytes] # fee_rhash -> rhash
         for k, swap in self.swaps.items():
             if swap.is_reverse and swap.prepay_hash is not None:
                 self.prepayments[swap.prepay_hash] = bytes.fromhex(k)
@@ -173,6 +187,7 @@ class SwapManager(Logger):
                 continue
             swap.funding_txid = txin.prevout.txid.hex()
             swap._funding_prevout = txin.prevout
+            self._add_or_reindex_swap(swap)  # to update _swaps_by_funding_outpoint
             spent_height = txin.spent_height
             if spent_height is not None:
                 swap.spending_txid = txin.spent_txid
@@ -319,7 +334,7 @@ class SwapManager(Logger):
             funding_txid = None,
             spending_txid = None,
         )
-        self.swaps[payment_hash.hex()] = swap
+        self._add_or_reindex_swap(swap)
         self.add_lnwatcher_callback(swap)
         await self.network.broadcast_transaction(tx)
         return tx.txid()
@@ -418,7 +433,7 @@ class SwapManager(Logger):
             funding_txid = None,
             spending_txid = None,
         )
-        self.swaps[preimage_hash.hex()] = swap
+        self._add_or_reindex_swap(swap)
         # add callback to lnwatcher
         self.add_lnwatcher_callback(swap)
         # initiate payment.
@@ -429,6 +444,13 @@ class SwapManager(Logger):
         success, log = await self.lnworker.pay_invoice(invoice, attempts=10)
         return success
 
+    def _add_or_reindex_swap(self, swap: SwapData) -> None:
+        if swap.payment_hash.hex() not in self.swaps:
+            self.swaps[swap.payment_hash.hex()] = swap
+        if swap._funding_prevout:
+            self._swaps_by_funding_outpoint[swap._funding_prevout] = swap
+        self._swaps_by_lockup_address[swap.lockup_address] = swap
+
     async def get_pairs(self) -> None:
         assert self.network
         response = await self.network._send_http_on_proxy(
@@ -543,16 +565,10 @@ class SwapManager(Logger):
         return self.get_swap_by_claim_txin(txin)
 
     def get_swap_by_claim_txin(self, txin: TxInput) -> Optional[SwapData]:
-        for key, swap in self.swaps.items():
-            if txin.prevout == swap._funding_prevout:
-                return swap
-        return None
+        return self._swaps_by_funding_outpoint.get(txin.prevout)
 
     def is_lockup_address_for_a_swap(self, addr: str) -> bool:
-        for key, swap in self.swaps.items():  # TODO take lock? or add index to avoid looping
-            if addr == swap.lockup_address:
-                return True
-        return False
+        return bool(self._swaps_by_lockup_address.get(addr))
 
     def add_txin_info(self, txin: PartialTxInput) -> None:
         """Add some info to a claim txin.