EXPLAIN analyze
UPDATE ways w SET linestring = (
  SELECT ST_MakeLine(c.geom) AS way_line FROM (
    SELECT n.geom AS geom
    FROM nodes n INNER JOIN way_nodes wn ON n.id = wn.node_id
    WHERE (wn.way_id = w.id) ORDER BY wn.sequence_id
  ) c
) WHERE w.id IN (
  SELECT w.id
  FROM ways w INNER JOIN way_nodes wn ON w.id = wn.way_id
  WHERE wn.node_id = 226673199
  GROUP BY w.id
)

                                                                               QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 UPDATE ON ways w  (cost=453.88..2358396.69 ROWS=7 width=276) (actual TIME=789.523..789.523 ROWS=0 loops=1)
   ->  Nested Loop  (cost=453.88..2358396.69 ROWS=7 width=276) (actual TIME=584.222..584.229 ROWS=1 loops=1)
         ->  Subquery Scan ON "ANY_subquery"  (cost=453.88..454.02 ROWS=7 width=40) (actual TIME=196.982..196.984 ROWS=1 loops=1)
               ->  HashAggregate  (cost=453.88..453.95 ROWS=7 width=8) (actual TIME=196.969..196.970 ROWS=1 loops=1)
                     ->  Nested Loop  (cost=0.00..453.87 ROWS=7 width=8) (actual TIME=196.958..196.961 ROWS=1 loops=1)
                           ->  INDEX Scan USING idx_way_nodes_node_id ON way_nodes wn  (cost=0.00..254.35 ROWS=7 width=8) (actual TIME=105.769..105.770 ROWS=1 loops=1)
                                 INDEX Cond: (node_id = 226673199)
                           ->  INDEX Scan USING pk_ways ON ways w  (cost=0.00..28.49 ROWS=1 width=8) (actual TIME=91.180..91.182 ROWS=1 loops=1)
                                 INDEX Cond: (id = wn.way_id)
         ->  INDEX Scan USING pk_ways ON ways w  (cost=0.00..28.49 ROWS=1 width=244) (actual TIME=0.010..0.013 ROWS=1 loops=1)
               INDEX Cond: (id = "ANY_subquery".id)
         SubPlan 1
           ->  Aggregate  (cost=336820.44..336820.45 ROWS=1 width=128) (actual TIME=387.208..387.208 ROWS=1 loops=1)
                 ->  Nested Loop  (cost=0.00..336799.41 ROWS=1682 width=132) (actual TIME=36.152..386.563 ROWS=515 loops=1)
                       ->  INDEX Scan USING pk_way_nodes ON way_nodes wn  (cost=0.00..3344.46 ROWS=1682 width=12) (actual TIME=0.947..2.427 ROWS=515 loops=1)
                             INDEX Cond: (way_id = w.id)
                       ->  INDEX Scan USING pk_nodes ON nodes n  (cost=0.00..198.24 ROWS=1 width=136) (actual TIME=0.744..0.745 ROWS=1 loops=515)
                             INDEX Cond: (id = wn.node_id)
 Total runtime: 791.067 ms
(19 ROWS)